CVE-2026-9639 Authenticated Denial of Service via Malicious Backup Tarball in LXD
An authenticated user can cause a denial of service in LXD by uploading a malicious backup tarball that triggers a null pointer dereference.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-9639?
CVE-2026-9639 is a medium-severity vulnerability in Canonical LXD, published on 26 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-476
Which versions are affected by CVE-2026-9639?
It affects 1 product.
Products include Canonical Lxd.
How do I fix CVE-2026-9639?
Apply the vendor's patch.
Is CVE-2026-9639 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-9639 exists.
Other vulnerabilities in Canonical LXD
- CVE-2026-66897 Instance template path traversal allows arbitrary host file write as root
- CVE-2026-62420 Cross-project cluster migration bypasses project restrictions via cluster notification flag
- CVE-2026-63293 Arbitrary File Read/Write: metadata.yaml symlink in image allows host filesystem access as root
- CVE-2026-63294 Root RCE via image backup.yaml symlink
- CVE-2026-63296 Project restriction bypass via instance migration config override
Sources
Also known as DEBIAN-CVE-2026-9639, GHSA-j93m-3j9p-m5m8.