Search/Attackers exploit critical SharePoint flaw after PoC goes public (CVE-2026-55040)
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Attackers exploit critical SharePoint flaw after PoC goes public (CVE-2026-55040)

Attackers exploit critical SharePoint flaw after PoC goes public (CVE-2026-55040) Threat actors have begun exploiting a critical Microsoft SharePoint flaw following the release of proof-of-concept (PoC) exploit code by Rapid7. About CVE-2026-55040 Tracked as CVE-2026-55040, the vulnerability was patched by Microsoft as part of its July 2026 Patch Tuesday updates. “The authentication feature could be bypassed as this vulnerability allows impersonation,” Microsoft said. “Exploiting this vulnerability could allow an attacker to disclose files and modify data, but the attacker cannot impact the availability of the system.” Rapid7 researcher Stephen Fewer has published an in-depth technical analysis of the flaw, accompanied by proof-of-concept exploit code. “A remote unauthenticated attacker…

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9.1
In KEV
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Key vulnerabilities
CVE-2026-55040CVSS 9.1● KEV

Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.

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Attackers exploit critical SharePoint flaw after PoC goes public (CVE-2026-55040)
Attackers exploit critical SharePoint flaw after PoC goes public (CVE-2026-55040) Threat actors have begun exploiting a critical Microsoft SharePoint flaw following the release of proof-of-concept (PoC) exploit code by Rapid7. About CVE-2026-55040 Tracked as CVE-2026-55040, the vulnerability was patched by Microsoft as part of its July 2026 Patch Tuesday updates. “The authentication feature could be bypassed as this vulnerability allows impersonation,” Microsoft said. “Exploiting this vulnerability could allow an attacker to disclose files and modify data, but the attacker cannot impact the availability of the system.” Rapid7 researcher Stephen Fewer has published an in-depth technical analysis of the flaw, accompanied by proof-of-concept exploit code. “A remote unauthenticated attacker can leverage CVE-2026-55040 to bypass authentication on a vulnerable SharePoint server, and perform operations as a SharePoint site user or administrator. The vulnerability is due to several issues in the JWT token validation pipeline,” Fewer explained. Threat intelligence firm Defused warned on X that attackers are now using the Rapid7 POC for CVE-2026-55040 against its SharePoint honeypots. Microsoft has yet to confirm the bug has been exploited in the wild, even as it flags the flaw as a likely target. When paired with another vulnerability, CVE-2026-63520, CVE-2026-55040 “could lead to unauthenticated remote code execution against a vulnerable SharePoint server”, according to NHS England Digital. CISA is warning administrators to harden their SharePoint deployments, citing active exploitation of several other vulnerabilities in the platform. Defenders were also urged to follow Microsoft’s official SharePoint hardening documentation. “Avoid exposing SharePoint Servers directly to the internet unless necessary; and if necessary, only configure a SharePoint Server behind a Layer 7 reverse proxy or equivalent application-layer security control that requires authentication and can inspect and filter requests,” CISA wrote.
helpnetsecurity.comAug 13, 2026extracted
Attackers Exploit SharePoint Authentication Bypass After Public PoC Release
Threat actors have begun to exploit a newly disclosed Microsoft SharePoint vulnerability following the release of a proof-of-concept (PoC) code. The vulnerability in question is CVE-2026-55040 (CVSS score: 9.1), which refers to a critical security feature bypass that stems from weak authentication. It was patched by Microsoft as part of its July 2026 Patch Tuesday updates. "The authentication feature could be bypassed as this vulnerability allows impersonation," Microsoft said in an advisory for the flaw last month. "Exploiting this vulnerability could allow an attacker to disclose files and modify data, but the attacker cannot impact the availability of the system." According to Defused Cyber, threat actors are leveraging a PoC exploit released by Rapid7 earlier this week, once again indicating fresh flaws are being rapidly abused in real-world attacks. It's worth mentioning that CVE-2026-55040 is the fifth SharePoint vulnerability to be exploited this year after CVE-2026-45659, CVE-2026-56164, CVE-2026-58644, and CVE-2026-50522. Successful exploitation of CVE-2026-55040 can allow an unauthenticated attacker to sidestep authentication on a vulnerable SharePoint server and perform arbitrary operations as a SharePoint site user or administrator. The vulnerability, per Rapid7, is due to "several issues" in the JWT token validation pipeline. Specifically, it chains four different weaknesses to allow an unauthenticated remote attacker to forge a valid JWT and impersonate any SharePoint site user. Rapid7 said the issue resides in two different classes that implement the token parsing and validation logic for Bearer service-to-service (S2S) tokens - SPJsonWebSecurityTokenHandlerV2 SPJsonWebSecurityBaseTokenHandlerV2 The entire chain can be exploited by an attacker as follows - Attacker sends a JWT with "alg: none" in the outer header, so no signature is required in the outer token. The actor token's x5t header contains SharePoint's own STS certificate thumbprint, making it possible to resolve a signing key with no verification. The resolved certificate is not in TrustedSecurityTokenServices, allowing the issuer to be accepted. The actor token's signature is a non-empty value, e.g., AAAA, which is never verified. Rapid7's Python-based PoC uses the forged JWT token to query a target's domain controller, enumerate users by SID, and auto-locate the SID for the user to find a site administrator. As of writing, it's unclear who is behind the exploitation activity or what their end goals are. Telemetry data captured by KEVIntel shows that a total of 12 exploitation attempts were recorded since July 19, 2026. Out of these, eight took place on August 12 and 13, 2026, indicating that the release of the PoC has played a role in these efforts. The 12 exploitation attempts have originated from eight unique IP addresses corresponding to five countries and regions, including Hong Kong, Japan, the Netherlands, Taiwan, and the U.S. In light of a spike in active exploitation, SharePoint users are advised to keep their instances up-to-date for optimal protection.
thehackernews.comAug 13, 2026extracted
Researchers Disclose AI-Assisted SharePoint Exploit Chain Reaching Unauthenticated RCE
Security researchers found a way to enter Microsoft SharePoint servers as any user, including an administrator, with no valid account. A significant part of the work that found it was done through an AI agent. The flaw, tracked as CVE-2026-55040 (CVSS 9.1), affects SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016. Microsoft's affected-product list covers only those three on-premises editions, and SharePoint Online is not among them. It lets a remote unauthenticated attacker assume a chosen user's identity. The attack has one prerequisite: the intruder has to know which account they want to become, either by its Active Directory security identifier (SID) or its user principal name (UPN), which is formatted like an email address. Rapid7 then chained the bypass to a separate remote code execution flaw and ran code on the server with no credentials. Microsoft and the firm disclosed that second flaw on August 11 as CVE-2026-63520 (CVSS 8.1), an unsafe .NET type instantiation in SharePoint's Business Connectivity Services. Exploiting it runs attacker code as the Windows service account behind the site. It reaches further than the bypass: Subscription Edition, 2019, and 2016 are all affected, along with Project Server 2013 Service Pack 1 and Office Web Apps 2013 Service Pack 1. Rapid7 says the flaw is fixed, but Microsoft's SharePoint update history listed no August package for any edition at the time of writing, so the build numbers carrying that fix are not yet public. Anyone running SharePoint on-premises should confirm the July update is installed, which Rapid7 says breaks the chain, and apply the August update when it appears. CISA said on July 14 that the bypass was not yet known to have been exploited. The bypass sits in SharePoint's JSON Web Token (JWT) validation pipeline. Rapid7 says several issues in that pipeline let an unauthenticated attacker act as the target user. Its proof-of-concept queries the target's domain controller to enumerate users by SID, then uses the bypass until it identifies the site administrator. In that demonstration, the prerequisite was less of a barrier than it sounds. CISA's assessment of the flaw, filed to the National Vulnerability Database on July 14, marks the attack automatable and its technical impact total. The firm published its full technical analysis and a proof-of-concept script on August 11. Rapid7 ran two research sprints against the SharePoint codebase, in January and March 2026. January produced no usable chain. March did: the firm says a heavily prompted agent helped produce the two-vulnerability path. Across 24 active days of agentic work, Rapid7 recorded 96 sessions, 256 prompts, and roughly 80,000 tool calls. A fully automated approach would not have worked, the firm says, because the model too often produced findings that were questionable or inaccurate, and an expert had to steer the agent. The firm also says the agent cheated. It overstepped its guidance to reach the goal, replaying admin credentials, enabling debug flags, and reading secrets, none of which were in the original threat model. Microsoft shipped the July fix in three server updates: Subscription Edition KB5002882, build 16.0.19725.20434 SharePoint Server 2019 KB5002883, build 16.0.10417.20175 SharePoint Server 2016 KB5002891, build 16.0.5561.1001 July 14 was also the end-of-support date for SharePoint Server 2016 and 2019. Microsoft's lifecycle guidance says products past end of support receive no new security updates. Both are on the affected list for the newly disclosed RCE, and Rapid7 tells customers of affected products to install the latest update. Whether Microsoft ships one for the two versions it stopped supporting in July is unresolved. For those farms, the exposure that matters is what comes next. The July update is said to break this chain; flaws found from here on would not be fixed under the published lifecycle. Three other SharePoint flaws were under active exploitation when CISA published its July 14 alert. The agency said attackers were stealing IIS machine keys and urged organizations to hunt for and remove harvesting artifacts before rotating those keys. Signs of compromise on an exposed SharePoint server call for incident response, not just a key rotation.
thehackernews.comAug 11, 2026extracted
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SmartApeSG campaign uses ClickFix page to push Remcos RAT, (Sat, Mar 14th)
Introduction This diary describes a Remcos RAT infection that I generated in my lab on Thursday, 2026-03-11. This infection was from the SmartApeSG campaign that used a ClickFix-style fake CAPTCHA page. My previous in-depth diary about a SmartApeSG (ZPHP, HANEYMANEY) was in November 2025, when I saw NetSupport Manager RAT. Since then, I've fairly consistently seen what appears to be Remcos RAT from this campaign. Finding SmartApeSG Activity As previously noted, I find SmartApeSG indicators from the Monitor SG account on Mastodon, and I use URLscan to pivot on those indicators to find compromised websites with injected SmartApeSG script. Details Below is an image of HTML in a page from a legitimate but compromised website that shows the injected SmartApeSG script. Shown above: Page from a legitimate but compromised site that highlights the injected SmartApeSG script. The injected SmartApeSG script generates a fake CAPTCHA-style "verify you are human" page, which displays ClickFix-style instructions after checking a box on the page. A screenshot from this infection is shown below, and it notes the ClickFix-style script injected into the user's clipboard. Users are instructed to open a run window, paste the script into it, and hit the Enter key. Shown above: Fake CAPTCHA page generated by a legitimate but compromised site, showing the ClickFix-style command. I used Fiddler to reveal URLS from the HTTPS traffic, and I recorded the traffic and viewed it in Wireshark. Traffic from the infection chain is shown in the image below. Shown above: Traffic from the infection in Fiddler and Wireshark. After running the ClickFix-style instructions, the malware was sent as a ZIP archive and saved to disk with a .pdf file extension. This appears to be Remcos RAT in a malicious package that uses DLL side-loading to run the malware. This infection was made persistent with an update to the Windows Registry. Shown above: Malware from the infection persistent on an infected Windows host. Indicators of Compromise Injected SmartApeSG script injected into page from legitimate but compromised site: hxxps[:]//cpajoliette[.]com/d.js Traffic to domain hosting the fake CAPTCHA page: hxxps[:]//retrypoti[.]top/endpoint/signin-cache.js hxxps[:]//retrypoti[.]top/endpoint/login-asset.php?Iah0QU0N hxxps[:]//retrypoti[.]top/endpoint/handler-css.js?00109a4cb788daa811 Traffic generated by running the ClickFix-style script: hxxp[:]//forcebiturg[.]com/boot <-- 302 redirect to HTTPS URL hxxps[:]//forcebiturg[.]com/boot <-- returned HTA file hxxp[:]//forcebiturg[.]com/proc <-- 302 redirect to HTTPS URL hxxps[:]//forcebiturg[.]com/proc <-- returned ZIP archive archive with files for Remcos RAT Post-infection traffic for Remcos RAT: 193.178.170[.]155:443 - TLSv1.3 traffic using self-signed certificate Example of ZIP archive for Remcos RAT: SHA256 hash: b170ffc8612618c822eb03030a8a62d4be8d6a77a11e4e41bb075393ca504ab7 File size: 92,273,195 bytes File type: Zip archive data, at least v2.0 to extract, compression method=deflate Example of saved file location: C:\Users\[username]\AppData\Local\Temp\594653818\594653818.pdf Of note, the files, URLs and domains for SmartApeSG activity change on a near-daily basis, and the indicators described in this article are likely no longer current. However, the overall patterns of activity for SmartApeSG have remained fairly consistent over the past several months. --- Bradley Duncan brad [at] malware-traffic-analysis.net
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Mar 14, 2026
Iranian APT Intrusion Masquerades as Chaos Ransomware Attack
Likely perpetrated by MuddyWater, the attack combined social engineering, persistence, credential harvesting, and data theft. The post Iranian APT Intrusion Masquerades as Chaos Ransomware Attack appeared first on SecurityWeek .
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May 7, 2026
Microsoft patches 400+ vulnerabilities, one zero-day under attack (CVE-2026-68820)
Microsoft patches 400+ vulnerabilities, one zero-day under attack (CVE-2026-68820) Microsoft’s August 2026 Patch Tuesday delivered security fixes for 400+ vulnerabilities, including one that has been exploited in zero-day attacks (CVE-2026-68820) and three that were publicly disclosed prior to the release of the patches. Vulnerabilities of note CVE-2026-68820 is a use-after-free flaw that affects the Windows Ancillary Function Driver for WinSock (AFD.sys) and allows a low-privileged local attacker to elevate privileges to SYSTEM. “A locally authenticated attacker could run a specially crafted application on an affected system to trigger a race condition,” Microsoft explained. “User interaction is not required.” Check Point researchers reported that the vulnerability has been exploited by North Korean attackers to deploy a kernel-mode rootkit in a new wave of the Operation Dream Job campaign. The three publicly disclosed vulnerabilities are: CVE-2026-62832, a vulnerability in the Windows User Profile Service that may allow an authenticated attacker to achieve Admin privileges by running a specially crafted application. “This is the flaw behind ‘LegacyHive,’ the unpatched proof-of-concept released by researcher Nightmare-Eclipse just hours after July’s Patch Tuesday,” commented Chris Goettl, VP of Product Management for security products at Ivanti. “This vulnerability lets a standard user coerce the User Profile Service into loading another user’s registry hive – including an administrator’s – to gain unauthorized access to that user’s Classes registry data.” CVE-2026-72971 affects the Windows Container Isolation FS Filter Driver (unionfs.sys), which may allow authenticated attackers to tamper with a vulnerable system. (This one only affectes Windows 11 versions for ARM64-based Systems.) Crowdstrike flagged a third vulnerability that was publicly disclosed before the patch was made available: CVE-2026-62737, a elevation of privilege vulnerability affecting the Windows kernel “While not officially recognized by Microsoft as publicly disclosed, a Chinese-language blog was published on August 9, 2026, describing a proof-of-concept exploit that can cause a system crash,” the company noted. Other vulnerabilities of note fixed this month include: CVE-2026-62815, a critical Microsoft QUIC vulnerability that can be exploited by unauthenticated attackers by sending a specially crafted packet to an affected service over the network. “Successful exploitation could allow the attacker to execute code on the target system. No authentication or user interaction is required,” Microsoft says. CVE-2026-62878, a stack-based buffer overflow vulnerability in Windows DNS that can lead to remote code execution. This one can also be easily, reliably and remotely exploited by unauthenticated attackers. CVE-2026-63520, in Microsoft Sharepoint, discovered by Rapid7 researchers. It can be used in conjunction with CVE-2026-55040, a previously patched Sharepoint flaw, to achieve unauthenticated remote code execution against a vulnerable server. A Microsoft Defender zero-day exploit In related news, the security researcher who goes by “Nightmare Eclipse” released a proof-of-concept (PoC) exploit that ostensibly bypasses the patch for CVE-2026-50656, the “RoguePlanet” Microsoft Defender vulnerability the company pushed out in July 2026. Dubbed “ShieldBreak” by the researcher, the vulnerability professedly affects Windows 11, 10 and Windows Server 2025. Vulnerability analyst Will Dormann confirmed that the PoC exploit works if Defender is enabled. Security researcher and former Microsoft employee Kevin Beaumont noted that the ShieldBreak exploit (aka RoguePlanet 2) “operates very differently” that the initial RoguePlanet exploit. “RoguePlanet was a filesystem race condition vuln that uses virtual disks and NT native file manipulation to trick quarantine process into overwriting system files. ShieldBreak user-mode callback hook to change file contents during a Defender cloud-hydration scan via cfapi (Cloud Filter API),” he explained, and released detections and hunting queries for the latter. He confirmed that ShieldBreak works on the latest Windows 11 version. Vulnerability analyst Will Dormann confirmed that the PoC exploit works if Defender is enabled and he also thinks ShieldBreak doesn’t seem to be a RoguePlanet bypass. Don’t rush and test patches “This volume of updates indeed seems to be the new normal – at least for now. What is interesting is that, while there is an explosion of bugs being reported (and fixed), there has been no equivalent increase in the number of bugs being actively exploited, at least as 0-days,” says Dustin Childs, head of threat awareness at TrendAI’s Zero Day Initiative. He also pointed out that Microsoft listing actively exploited bugs as “Unproven” or downplaying working Pwn2Own exploits may force security teams to perform independent risk triage. Ivanti’s Goettl says that the patches need to be triaged to identify CVEs that require immediate attention and that organizations need to remember that CVEs with high CVSS scores but which are not exploited or are not in internet-facing systems can be handled in a second round of patching. Tyler Reguly, Associate Director, Security R&D at Fortra, says that despite the latest mega-updates, IT admins and security teams should keep calm and not rush updates: “You need to make sure that you are rolling out safe updates that will not negatively impact your systems.” His advice for CISOs is to talk to their teams about how they are shifting or modifying their workflows to better accommodate this patching shift, and support them by enabling the changes they want to see made. UPDATE (August 13, 2026, 04:10 a.m. ET): The section about the ShieldBreak exploit has been rewritten to reflect new insight from security researchers who tested it. Subscribe to our breaking news e-mail alert to never miss out on the latest breaches, vulnerabilities and cybersecurity threats. Subscribe here!
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Aug 12, 2026
Hackers exploit Sangoma Switchvox flaw to deploy reverse shells
Malware linked to break-ins at F5 BIG-IP Access Policy Manager appliances hides a PHP web shell in memory instead of in a file on disk, Sophos said in an analysis published on September 7. When Apache loads any of the three appliances' own PHP scripts, the malware adds the web shell to the copy held in memory, so a check of the file on disk can come back clean. Those three scripts are the same ones F5 pointed customers to in March, when it said changes to them alone do not show a break-in. A web shell is usually a small script an attacker drops into a web server's folders to run commands through ordinary web requests. Because it sits on disk, defenders look for it by scanning files and comparing them against known-good copies. That approach does not work here. As the researchers put it, the web shell "does not need to exist in its final form on disk." The three scripts are apm_css.php3, full_wt.php3 and webtop_popup_css.php3, part of the BIG-IP APM webtop. F5 named all three in March in a published list of indicators of compromise for the malware it tracks as c05d5254, and said at the time that their presence alone does not point to a security problem. F5 also said it had seen cases where a web shell was written to disk, but that the web shells "have been observed to work in memory only," which means the files it listed might not be modified. The Sophos analysis explains how both statements can be true at once. Sophos examined a single sample. Its analysis names no victim and does not say how the sample was obtained. F5 has linked the c05d5254 activity to appliances affected by CVE-2025-53521, Sophos said. F5 first published that flaw on October 15, 2025, as a denial-of-service problem. On March 27, 2026, F5 said new information had led it to reclassify the flaw as remote code execution, and that it had been exploited. An attacker needs no login to use it, and F5 rates it 9.8 on CVSS 3.1 and 9.3 on CVSS 4.0. CISA added it to its Known Exploited Vulnerabilities catalog the same day, giving U.S. federal civilian agencies until March 30 to act. The flaw applies where a BIG-IP APM access policy is set on a virtual server. The UK's National Cyber Security Center calls BIG-IP APM a common component, especially in large organizations. F5's advisory lists the affected and fixed releases. The patch that fixes this is nearly a year old. Ireland's National Cyber Security Center said in a March 31 advisory that the patch released in October is still valid and will protect against exploitation. The web shell is the last step in a longer chain, and the earlier steps do touch the disk. Sophos said a separate installer, found in a sample named umount, infects the Apache web server program at /usr/sbin/httpd by adding malicious code to the front of the real file. The size of that added code matches the payload carried inside the installer, which Sophos said strongly suggests the installer puts it there. ESET, which analyzed related samples in April and named the malware PoisonedRefresh, said the installer is meant to be run as root and turns off SELinux. It also infects umount, httpd and rc.local inside BIG-IP install images, which ESET said was presumably done to spread the malware to other systems through the installation media. Because the malware sits inside the Apache program, it runs before Apache's own code starts. Sophos said it hooks an Apache Portable Runtime function, apr_dso_load, and does nothing until Apache loads the PHP module, libphp. Once PHP is loaded, the malware reads /proc/self/maps to find the module in memory, briefly makes those memory pages writable, rewrites the calls the module uses to open, size, and map files, then puts the original permissions back. From that point, it controls what PHP sees when it opens one of the three scripts. When the file is mapped into memory, the malware places the web shell in front of the original content. The web shell reads the raw body of a request, checks it for a short marker, decrypts the rest, and runs it. It replies with HTTP status 201 and a CSS content type, so the exchange looks like a request for a stylesheet. The malware also opens a local socket at /run/bigtlog.pipe. After checking for a fixed token, it connects that socket to /bin/bash, giving an interactive shell without opening a network port. Sophos said it could not find any code in the sample for connecting to that socket, and no other use of the token, so the two ways in look like separate features. It has no evidence either way on whether the attacker reaches the socket through the web shell. What Defenders Can Check Sophos said its behavioral signals are leads to investigate, not proof on their own, and should be read alongside file, process, and memory evidence. The list below combines them with the indicators F5 published in March. File: /run/bigtlog.pipe or /run/bigstart.ltm present Binary: hash, size or timestamp mismatch on /usr/bin/umount or /usr/sbin/httpd against a known good copy. F5 notes that sizes and timestamps differ between releases and engineering hotfixes Tool: sys-eicheck failing because one of those two files has changed Log: an entry in /var/log/restjavad-audit showing a local user reaching the iControl REST API from localhost Log: an entry in /var/log/auditd showing SELinux being switched off by the same route Log: an entry in /var/log/audit showing a bash command run through iControl REST. F5 says these lines show base64 data written into a file and /run/bigstart.ltm being run Traffic: HTTP 201 responses carrying a CSS content type from the appliance Host behavior: an Apache worker reading /proc/self/maps, changing memory permissions around libphp, binding a socket under /run, or starting /bin/bash SHA-256: 26bd5b0722d1dbab5db749a063c49bc8638653ac2addfead7a9cb3d6d57bccc9 File, weak on its own: changes to the three .php3 scripts. F5 says their presence alone does not show a problem, and the Sophos analysis explains why: the file does not have to change at all F5's list also includes items the Sophos analysis does not cover, among them /run/bigstart.ltm and the changes affecting sys-eicheck. Neither account describes the whole intrusion. If You Have Already Patched Patching does not settle whether an appliance was compromised before the patch went on. Ireland's NCSC said no timeline for exploitation is available, and that it expects some exploitation was or could have been happening before the flaw and its fix were first published in October 2025. The UK's NCSC advises investigating for compromise "regardless of when the system was updated." Run F5's built-in sys-eicheck integrity check. F5's own indicators say the changes to /usr/bin/umount and /usr/sbin/httpd make this tool fail, so a failure is itself the signal. Collect a qkview report, send it to F5 and raise a case. Ireland's NCSC said F5 can check that report for signs of compromise, and that raising an associated case brings a quicker and fuller response. Compare the contents of modules in memory against the copies on disk, which Sophos recommends adding to incident response playbooks for critical web servers. Where a full investigation is not possible, the UK NCSC advises isolating the appliance and rebuilding it as new, and says this may cause an outage. Three things are still unknown. F5 has not said when exploitation began. None of the published advisories or analyses say whether upgrading an appliance to a fixed release removes malware already installed on it, and both Sophos and ESET describe a component designed to survive upgrade images. And no one has named an attacker: Sophos said it does not have enough evidence to name a group, and ESET said in April that it had not settled the question either.
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Sep 9, 2026
Microsoft Plugs Nearly 1,000 Security Holes
Adobe on Monday released security patches to address a maximum-severity flaw impacting Adobe Commerce and Magento Open Source that has come under active exploitation in the wild. The vulnerability, now tracked as CVE-2026-75650 (CVSS score: 10.0), has been codenamed StyleSmuggler by Sansec, which discovered zero-day exploitation starting September 4, 2026. "This update resolves a critical vulnerability that could result in arbitrary code execution," Adobe said, adding it's "aware that CVE-2026-75650 has been exploited in the wild targeting Adobe Commerce merchants." At its core, the flaw abuses Magento's template system through PHP code injection to generate a "Payment Transaction Failed Reminder" email, triggering code execution in the process. The shortcoming affects the following versions - Adobe Commerce - 2.4.9-2026-aug and earlier - 2.4.8-2026-aug and earlier - 2.4.7-2026-aug and earlier - 2.4.6-2026-aug and earlier - 2.4.5-2026-aug and earlier - 2.4.4-2026-aug and earlier Adobe Commerce B2B - 1.5.3-2026-aug and earlier - 1.5.2-2026-aug and earlier - 1.4.2-2026-aug and earlier - 1.3.4-2026-aug and earlier - 1.3.3-2026-aug and earlier Magento Open Source - 2.4.9-2026-aug and earlier - 2.4.8-2026-aug and earlier - 2.4.7-2026-aug and earlier - 2.4.6-2026-aug and earlier Patches have been released as part of a hotfix's available for download from the following link: repo.magento[.]com/patch/VULN-39341-composer-patches.zip "To help resolve the vulnerability for the affected products and versions, you must apply the VULN-39341 patch (depending on your version) and rotate your encryption keys," Adobe said. The development comes days after the Dutch e-commerce security company revealed that threat actors are exploiting CVE-2026-75650 to deploy a Rust-based Linux backdoor that connects to an external server and awaits further instructions. Separately, the issue has been abused to deliver a PHP dropper on susceptible sites that writes a web shell capable of executing arbitrary PHP code. According to Netherlands-based Disrex, a Magento server managed by the e-commerce development platform is said to have been compromised 50 minutes after the first confirmed StyleSmuggler exploitation was reported on September 4, 2026, at 10:20 p.m. UTC. "StyleSmuggler turns Magento's own template-processing and dependency-injection code into an unauthenticated remote-code-execution chain," Disrex said. Telemetry data from Previdian shows that 12 exploitation attempts have been recorded against its honeypots since September 7, 2026, from two unique IP addresses from China and Romania. That said, the efforts have been unsuccessful, Founder and CEO Ryan Dewhurst said. Update The U.S. Cybersecurity and Infrastructure Security Agency (CISA), on September 8, 2026, added CVE-2026-75650 to its Known Exploited Vulnerabilities (KEV) catalog, requiring Federal Civilian Executive Branch (FCEB) agencies to apply the fixes by September 11, 2026. In tandem, Adobe has also released patches for more than 170 vulnerabilities across its products, including CVE-2026-82004 (CVSS score: 10.0), an operating system command injection flaw in Campaign Classic leading to arbitrary code execution. Also patched by Adobe are two critical vulnerabilities in ColdFusion CVE-2026-48273, CVSS score: 9.9, and CVE-2026-75746, CVSS score: 9.1) that could result in arbitrary code execution. The web design software maker said it's not aware of any exploits in the wild for any of these issues.
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Sep 9, 2026