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VulnerabilityPublished

CVE-2026-63297: Canonical LXD · Time-of-check Time-of-use (TOCTOU) Race Condition

Affects Canonical LXDSource CVE Database V5

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Not known to be exploited · CVSS 9.9 Critical : upgrade to 5.21.6 or 5.0.8 as a priority.

Data as of 11 Nov 2026, 23:24 UTC

CVSS 3.1 base score
9.9Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 5.21.6, 5.0.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.

What to do

Upgrade Canonical LXD to 5.21.6 or 5.0.8.

Affected software

ProductAffectedFixed in
CanonicalLXDAffected
  • >=5.21.0 <5.21.6
Fixed in
  • 5.21.6
CanonicalLXDAffected
  • >=5.0.0 <5.0.8
Fixed in
  • 5.0.8
GitHubLXDpkg:github/LXDOther threatsAffected
  • >=5.0.0 <5.0.8
  • >=5.21.0 <5.21.6
Fixed in
  • 5.0.8
  • 5.21.6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, administrators should exercise caution when performing cross-project instance copies and consider restricting such operations to trusted users only.

Description

An authorization bypass vulnerability in LXD due to a timing flaw during configuration merging allows an authenticated attacker to bypass target project restrictions during cross-project instance copies. When copying an instance to a target project, LXD performs restriction checks before configuration merging is complete, creating a time-of-check to time-of-use (TOCTOU) condition. An attacker can exploit this flaw to copy instances with disallowed high-privilege configurations into restricted projects, bypassing security controls.

References

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