Google Project Zero (Organization): news timeline & CVEs

Windows COM Flaw Lets Attackers Gain SYSTEM Privileges With a Malicious DLL

Project Zero details CVE-2026-66804, a Windows COM flaw giving SYSTEM via planted DLL; patched in August, PoC and commercial module public.

CVE-2026-66804 (CVSS 7.8, High) lets an authenticated local user plant a malicious DLL in %PROGRAMDATA%\CrossDevice\ that a SYSTEM process loads through a dangling COM registration for the Windows CrossDevice component, chained via custom COM marshaling in the Shell Create Object Handler. It is an incomplete fix for the earlier 'Dark Elevator' bug CVE-2026-50343. Microsoft patched it in the August 2026 Patch Tuesday, but public PoC code has surfaced and at least one commercial exploitation module automates the LOCAL SERVICE-to-SYSTEM chain.

Cyber Security NewsSep 22, 09:45 UTC · 5d agoExploit / PoC 2 sources CVE-2026-66804 CVE-2026-50343

Windows Exploitation Techniques: Dangling COM Object Registrations

Project Zero details patched Windows CVE-2026-66804, a privilege escalation via a dangling COM registration.

Google Project Zero describes CVE-2026-66804, a Windows local privilege escalation that Microsoft has fixed and that the author and 14 others reported. It is an incomplete fix for CVE-2026-50343, previously dubbed Dark Elevator. A system-wide COM registration for the CrossDevice class referenced a missing DLL under ProgramData, a directory local users can create, so a planted library could be loaded into a privileged process. After the earlier installer-service path was closed, the post explains that custom COM marshaling could still target a privileged service that had not disabled it.

Google Project Zeroupdated Sep 22, 09:45 UTC · 5d agofirst Sep 21, 07:00 UTC · 6d agoResearch 2 sources CVE-2026-50343 CVE-2026-668041

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Windows COM Flaw Lets Attackers Gain SYSTEM Privileges With a Malicious DLL

Windows Exploitation Techniques: Dangling COM Object Registrations