Bootc defaults to a permissive containers signature policy that permits unsigned content when using mutable image tags. The flaw allows an attacker who can alter the tag in a registry that accepts any content to replace the signed image with unsigned material. When the host performs a bootc update, the unsigned package is installed as root, giving the attacker full OS-level authority on reboot.

The vulnerability affects recent Red Hat products that rely on bootc, including Red Hat Enterprise Linux 8, 9 and 10, Red Hat Hardened Images, and Red Hat OpenShift Container Platform 4. Any installation using the default containers policy and mutable image tags is potentially impacted.

The issue has a CVSS score of 8.1, indicating a high severity. EPSS data is not available, but the lack of a low exploitation probability metric does not reduce the risk; the flaw permits major privilege escalation through unsigned updates. The vulnerability is not yet listed in the CISA KEV catalog. An attacker must gain write access to a registry that enables an unsigned mutable tag, a capability that is common in shared registry environments or compromised registries. Once the tag is tweaked, the host will reboot with the attacker’s code as root.