PoC exploit released for critical AD CS domain-takeover flaw (CVE-2026-54121) Security researchers who discovered and reported CVE-2026-54121 (aka “Certighost”), a critical privilege elevation vulnerability in Active Directory Certificate Services (AD CS), have released a proof-of-concept (PoC) exploit for and technical details related to the flaw. The vulnerability AD CS is a Microsoft Windows Server role that lets an organization run its own Public Key Infrastructure (PKI). It acts as a Certificate Authority (CA), issuing and managing digital certificates used for authentication, encryption, and signing across a network. CVE-2026-54121 is a critical improper-authorization flaw with a CVSS score of 8.8. “An authenticated attacker could manipulate attributes associated with a machine…