CVE-2026-40251: linuxcontainers incus Improper Validation of Array Index

Vulnerability summary

CVE-2026-40251 is a high (CVSS 7.1) Improper Validation of Array Index vulnerability in linuxcontainers incus. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 39.3% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 06-05-2026
   PublishedVulnerability first disclosed.
2. 07-05-2026
   Last modifiedVulnerability information updated.

Description

Incus is a system container and virtual machine manager. In versions before 7.0.0, missing validation logic in the storage volume import logic allows an authenticated user with access to the storage volume feature to cause the Incus daemon to crash. The backup restore subsystem contains an out-of-bounds panic vulnerability caused by an invalid bounds check when indexing snapshot metadata arrays, and the same flawed pattern also appears in the migration path. When iterating through physical snapshots provided in a backup archive, the loop uses the index to look up corresponding metadata in the parsed `Config.Snapshots` and `Config.VolumeSnapshots` slices. The guard condition `len(slice) >= i-1` is incorrect because it can still evaluate to true when the subsequent slice[i] access is out of bounds. An attacker can submit a backup archive that contains physical snapshot directories while supplying a tampered `index.yaml` with an empty or truncated snapshot metadata array, causing the daemon to index beyond the end of the metadata slice and crash. Repeated use of this issue can be used to keep Incus offline, causing a denial of service. This issue is fixed in version 7.0.0.

• CWE-129Improper Validation of Array IndexThe product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.