An improper sanitization of the compression_algorithm parameter in Canonical LXD allows an authenticated, unprivileged user to execute commands as the LXD daemon on the LXD server via API calls to the image and backup endpoints. This issue affected LXD from 4.12 through 6.6 and was fixed in the snap versions 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 channel 4.0/stable is not affected as it contains version 4.0.10.
https://github.com/canonical/lxd/security/advisories/GHSA-4rmf-rcp8-2r9g
https://github.com/canonical/lxd/commit/b7b411caf5c4971bfe2386c72128f44d7e2aaf4f
https://github.com/canonical/lxd/commit/7046979645c2ce1b63b2f9e60ddf6cbc4c4b78f9
https://github.com/canonical/lxd/commit/043696a13171ace7dd4c2b32d34ce039ab629052
https://discourse.ubuntu.com/t/lxd-authenticated-remote-code-execution-fixes-available/78365
Published: 2026-03-12
Updated: 2026-03-13
Base Score: 6.8
Vector: CVSS2#AV:N/AC:L/Au:S/C:C/I:N/A:N
Severity: Medium
Base Score: 8.8
Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity: High
Base Score: 9.4
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Severity: Critical
EPSS: 0.00116