
CVE-2026-45585 (YellowKey) — BitLocker bypass zero-day with public PoC. How are you handling TPM+PIN rollout at scale?
So CVE-2026-45585 dropped publicly on May 19 and I've been going through the technical details. The short version: an attacker with physical access can inject autofstx.exe into the BootExecute value inside the WinRE image. That binary runs pre-OS, completely before your EDR stack initialises, and it bypasses BitLocker's pre-boot authentication entirely.
Affected: Windows 11, Server 2022, Server 2025.
No patch yet — just Microsoft's 6-step manual WinRE mitigation (mount → load hive → remove autofstx.exe → unload → unmount/commit → reagentc disable/enable cycle) and the recommendation to move from TPM-only to TPM+PIN.
A few things I'm genuinely curious about from a practical ops standpoint:
- For those managing large Windows fleets — what's your current rollout strategy for TPM+PIN enforcement at scale? Intune, GPO, something else? Any gotchas with user PIN resets in a helpdesk-heavy environment?
- The WinRE mitigation has to be applied per-machine. Is anyone scripting this and if so how are you handling the fact that reagentc operations occasionally fail silently on certain hardware configs?
- Physical access attacks are often dismissed as "out of scope" in threat models. Does something like YellowKey — with a public PoC — change how your organisation frames physical device loss in risk assessments?
The public PoC on GitHub is the part that concerns me most. This isn't theoretical anymore — the barrier to exploitation just dropped significantly.
I previously covered the Microsoft MDASH story (AI finding 16 Windows zero-days) here if you want background on the broader Windows security picture: https://www.techgines.com/post/microsoft-mdash-agentic-ai-security-windows-vulnerabilities
Full technical breakdown at TechGines: https://www.techgines.com/post/cve-2026-45585-bitlocker-bypass-yellowkey-zero-day