CVE-2026-9639 is a medium-severity (CVSS 6.5) NULL Pointer Dereference vulnerability. A fix is available — see the affected versions and patch details below.
Authenticated Denial of Service via Malicious Backup Tarball in LXD
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-9639.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Description
Nil-pointer dereference in CreateCustomVolumeFromBackup in LXD up to version 6.8 and 5.21 on Linux allows an authenticated user with can_create_storage_volumes permissions to cause a denial of service via a specially crafted custom-volume backup tarball that omits the expires_at snapshot field.
Affected Products
lxdcanonicalDetection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Fix
Upgrade the affected component to the fixed release for CVE-2026-9639, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2026-9639 in your dependencies?
Find it across your dependency tree, including transitive dependencies.