// #cve-2026-33826
2 articles
BeigeBurrow: New Go-Based Covert C2 Agent Deployed via Active Directory RCE CVE-2026-33826
A previously undocumented post-exploitation tool named BeigeBurrow has been observed in at least two enterprise intrusions following exploitation of the Windows Active Directory RCE CVE-2026-33826. The Go-based agent uses HashiCorp's Yamux library to multiplex covert relay channels over port 443, blending into encrypted enterprise traffic. CVE-2026-33826 was patched in April Patch Tuesday; organisations that have not yet applied the patch should treat it as urgent.
CVE-2026-33826: Windows Active Directory RCE via Crafted RPC Calls — Patch Now
A critical remote code execution flaw in Windows Active Directory allows any authenticated domain user to execute arbitrary code on domain controllers and other AD-joined servers by sending specially crafted RPC calls. Rated CVSS 8.0 and assessed by Microsoft as 'Exploitation More Likely', CVE-2026-33826 poses a serious lateral-movement and domain-compromise risk for every Windows Server environment. The April 2026 Patch Tuesday update provides the only full remediation.