LXD: crafted container image symlinks allow host file write and RCE (CVE-2026-48750, CVE-2026-48752)
Severity: critical · Patch status: patched · Since 2026-06-26 · CVE-2026-48749, CVE-2026-48750, CVE-2026-48752
Two critical LXD flaws, CVE-2026-48750 and CVE-2026-48752 (CVSS 9.9 per GitHub), let a crafted container image reach arbitrary host paths through top-level symlinks that LXD does not sanitise when it unpacks the image, which can end in root command execution. CVE-2026-48750 abuses an exec-output symlink so that the record-output feature writes execUUID.stdout and .stderr to an attacker-chosen host directory (the advisory's proof of concept targets /etc/cron.d). CVE-2026-48752 abuses a templates symlink for arbitrary host file read and write. A rootfs-symlink variant, CVE-2026-48749, is in the same LXD 5.21.5 release notes. Public proof-of-concept scripts are printed in the advisories. No in-the-wild exploitation is reported, the CVEs are not in CISA KEV, and EPSS is 0.78 percent. The same bugs exist in Incus, which fixed them in 7.2.0 (released 2026-06-26) and published its advisories that day; the LXD advisories were published on 2026-11-06. LXD fixes: 5.21.5 LTS (its release notes list both CVEs), 6.10.0 (the first 6.x release containing both fixes) and 6.7 (the first 6.x release with the CVE-2026-48752 fix). Fix status for LXD 5.0.x and Incus 6.x is not confirmed by any upstream source checked, so do not assume those lines are safe.
What to do
- Upgrade LXD to 5.21.5 (5.21 LTS) or 6.10.0 (6.x), or Incus to 7.2.0; confirm the fix status of LXD 5.0.x and Incus 6.x with upstream before treating them as fixed
- Only import images from trusted sources; treat community and untrusted image repositories as hostile
- Audit recently imported images for top-level exec-output, templates or rootfs symlinks
- Restrict who can import images and who can reach the LXD or Incus REST API or unix socket
- Check hosts for unexpected files such as cron entries in /etc/cron.d or exec_*.stdout artifacts
Fixed versions
- lxd-5.21.5 (5.21 LTS; release notes list CVE-2026-48750 and CVE-2026-48752)
- lxd-6.10.0 (first 6.x release with both fixes)
- lxd-6.7 (first 6.x release with the CVE-2026-48752 fix)
- github.com/lxc/incus/v7 7.2.0
- github.com/canonical/lxd 0.0.0-20260626085134-124f90100640 (main-branch commit for CVE-2026-48750; not contained in lxd-5.21.5)
- github.com/canonical/lxd 0.0.0-20260203144152-d1c8ba15d160 (main-branch commit for CVE-2026-48752)
Sources
All live incidents on Threat Watch
