The vulnerability arises from newline injection in environment variable handling during container initialization. An attacker who can launch a container through a custom YAML configuration can embed newline characters in an environment variable value, causing the Incus engine to split the value into multiple configuration directives. This effectively allows the insertion of arbitrary lifecycle hooks into the container’s LXC configuration. The injected hooks can execute arbitrary code on the host, leading to full host control and representing a severe Local Privilege Escalation flaw. This weakness is identified as CWE‑93.

The flaw exists in Incus version 6.20.0 and earlier. Users who belong to the incus group or have permission to create containers with custom YAML files can trigger the injection. The planned fix is slated for releases 6.0.6 and 6.21.0, which have not yet been made publicly available.

The CVSS base score is 8.7, indicating high severity, while the EPSS score of less than 1% suggests a low current exploitation probability. The vulnerability is not listed in the CISA KEV catalog. Since exploitation requires only local access to the Incus management interface and membership in the incus group, it does not depend on network exposure. An attacker can validate the payload by mounting /tmp from the host, a privileged operation reserved for validation steps. The attack surface is therefore limited to users with container creation permissions, and no known active exploitation has been reported.