The vulnerability arises from an insufficient TPM policy within IncusOS’s systemd-cryptenroll configuration. Key detail from description: a default PCR11 policy permits the TPM to release the LUKS master key to any system booting with the expected PCR7 value, even when a substituted root partition is present. This allows an attacker with physical access to replace the encrypted root partition, trigger the system to prompt for a recovery key, supply a crafted key, and then run a custom systemd unit on boot that retrieves the real root disk’s LUKS key via the TPM. The attacker can then obtain, use or alter the volume key to compromise the integrity and confidentiality of the original data. The impact is a full compromise of the encrypted Linux container operating system and the data stored therein, without alerting the owner or changing any Secure Boot state.

Affected products: IncusOS (lxc:incus-os). Versions before the release 202603142010 (3.14/2026-03-14 20:10 UTC) contain the flawed PCR11 logic. The vendor notes that the updated release includes a new PCR15 logic that automatically updates the TPM policy on boot, binding the LUKS keys to the correct registers and mitigating the flaw.

Severity: CVSS score 7.7 indicates high risk. Exploitability: The attack requires physical access to the machine, the ability to replace the root partition, and knowledge of the TPM policy. While such conditions reduce the likelihood compared to remote exploits, the vulnerability is still significant for any system exposed to physical tampering. EPSS score is not available, and the flaw is not listed in the KEV catalog. No workarounds exist; the only mitigation is to install the patched version or perform a full wipe and reinstall if the system may have already been accessed.