Incus improperly handles container images containing a duplicate top-level rootfs symlink that points to the host filesystem root. When such an image is imported and initialized, the stopped-container file API opens the rootfs path and passes it to a function that forks and chroots to this path. This allows an attacker to escape the container context and access or modify arbitrary files on the host with root privileges. A proof-of-concept demonstrates reading /etc/shadow and writing files to the host root directory by exploiting this symlink handling flaw.

The vulnerability allows an attacker with the ability to import and initialize container images in Incus to read and write arbitrary files on the host filesystem with root privileges. This can lead to disclosure of sensitive information, such as password hashes, and potentially arbitrary command execution on the host system, severely compromising host security.

A fix is available in Incus version 7.2.0 and later. Users should upgrade to version 7.2.0 or newer to remediate this vulnerability. Patch status is confirmed by the affectedVersions field indicating versions prior to 7.2.0 are vulnerable. No vendor advisory content was provided to indicate alternative mitigations or temporary fixes.