An authenticated unprivileged user can cause the LXD daemon to execute arbitrary commands by abusing the unsanitized compression_algorithm parameter on the image and backup API endpoints. This leads to remote code execution with the privileges of the LXD daemon, effectively granting the attacker full control over the host. The weakness is classified as OS Command Injection (CWE‑78).

The vulnerability affects Canonical’s LXD product, impacting all versions from 4.12 through 6.6. It was fixed in snap packages 5.0.6-e49d9f4 (channel 5.0/stable), 5.21.4-1374f39 (channel 5.21/stable), and 6.7-1f11451 (channel 6.0 stable). The 4.0/stable channel, containing version 4.0.10, is not affected.

The CVSS score of 9.4 marks this issue as critical. The EPSS score of less than 1% indicates a low probability of exploitation, but the attack requires only authenticated access to an unprivileged LXD user. The vulnerability is not yet listed in the KEV catalog, but its impact is severe because it affords control of the host system. The attack vector is through authenticated API calls to the image and backup endpoints, exploiting the missing sanitization of the compression_algorithm parameter.