github.com/canonical/lxd · LXD has arbitrary file write on host via `exec-output` symlink in crafted image
Affects github.com/canonical/lxdSource GCVE Database
CVSS 9.9 Critical : upgrade to 0.0.0-20260626085134-124f90100640 as a priority.
Data as of 6 Nov 2026, 19:04 UTC
- Patch
- Available – fixed in 0.0.0-20260626085134-124f90100640
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HWhat to do
Upgrade github.com/canonical/lxd to 0.0.0-20260626085134-124f90100640.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Gogithub.com/canonical/lxd | Affected
| Fixed in
|
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AI-suggested
A patch is available in version 0.0.0-20260626085134-124f90100640 and later. Users should upgrade to this fixed version to remediate the vulnerability. No other mitigations are indicated by the vendor advisory.
Description
LXD contains a vulnerability where the 'exec-output' directory can be a symlink, allowing files to be written to arbitrary locations on the host. This can be exploited to create files such as cron jobs, enabling arbitrary command execution on the host system. The issue arises because top-level symlinks in unpacked images are preserved, and the code follows the symlink when writing output files. A proof-of-concept demonstrates placing a malicious file in /etc/cron.d to achieve code execution.
References
- github.com/canonical/lxd/security/advisories/GHSA-9j25-mm2h-2f76 (opens in a new tab)
- github.com/lxc/incus/security/advisories/GHSA-73hr-m85f-64v9 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-48750 (opens in a new tab)
- github.com/canonical/lxd/commit/124f901006400f634d54d908911c9ea93bae9a70 (opens in a new tab)
- github.com/canonical/lxd/commit/254b85c9301397e25304116b63da9154093199da (opens in a new tab)
- github.com/canonical/lxd/commit/4cd63344f8a523acf39fdc02a80fd64b2e3b584f (opens in a new tab)
- github.com/canonical/lxd/commit/937b761393af48fe4f5ff7e610ebfc1c9144e953 (opens in a new tab)
- github.com/canonical/lxd/commit/bb0f2521a59edacff2a0cb2e9532fdfbe68cf764 (opens in a new tab)
- github.com/canonical/lxd (opens in a new tab)
- github.com/canonical/lxd/releases/tag/lxd-5.21.5 (opens in a new tab)
- manpages.debian.org/bookworm/cron/cron.8.en.html (opens in a new tab)