IncusOS has a LUKS encryption bypass due to insufficient TPM policy
Date: 2026-03
Affected: go/github.com/lxc/incus-os/incus-osd
Attack vector: auth-bypass
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-32606
CWE: CWE-522
CVSS: 7.6 (CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H)

The default configuration of systemd-cryptenroll as used by IncusOS through mkosi allows for an attacker with physical access to the machine to access the encrypted data without requiring any interaction by the system's owner or any tampering of Secure Boot state or kernel (UKI) boot image. That's because in this configuration, the LUKS key is made available by the TPM so long as the system has the expected PCR7 value and the PCR11 policy matches. That default PCR11 policy importantly allows for the TPM to release the key to the booted system rather than just from the initrd part of the signed kernel image (UKI). The attack relies on the attacker being able to substitute the original encrypted root partition for one that they control. By doing so, the system will prompt for a recovery key on boot, which the attacker has defined and can provide, before booting the system using the attacker's root partition rather than the system's original one. The attacker only needs to put a systemd unit starting on system boot within their root partition to have the system run that logic on boot. That unit will then run in an environment where the TPM will allow for the retrieval of the encryption key of the real root disk, allowing the attacker to steal the LUKS volume key (immutable master key) and then use it against the real root disk, altering it or getting data out before putting the disk back the way it was and returning the system without a trace of this attack having happened.


Mitigations:

Architectural layers (MAESTRO):