A now patched security vulnerability in Zimbra Collaboration was exploited as a zero-day earlier this year in cyber attacks targeting the Brazilian military. Tracked as CVE-2025-27915 (CVSS score: 5.4), the vulnerability is a stored cross-site scripting (XSS) vulnerability in the Classic Web Client that arises as a result of insufficient sanitization of HTML content in ICS calendar files, resulting in arbitrary code execution. "When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a tag," according to a description of the flaw in the NIST National Vulnerability Database (NVD). "This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as…