Bootc: containers-common: bootc: automatic updates can apply unsigned mutable-tag content under default containers policy

Overview

A flaw was found in bootc when operating with the default containers signature policy. Automatic or manual upgrades of a mutable image tag may apply unsigned content for registries that fall through to insecureAcceptAnything, allowing an attacker who can update that tag to execute arbitrary OS content as the host root filesystem on reboot.

Affected

• bootc (all versions)
• containers-common (all versions)
• container-tools:rhel8/containers-common (all versions)
• bootc (all versions)
• containers-common (all versions)
• bootc (all versions)
• containers-common (all versions)
• containers-common
• rhcos

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Workarounds

Pin bootc updates to image digests, or configure /etc/containers/policy.json to reject unsigned content by default and allow only explicitly trusted signed scopes. Until policy is hardened, disable automatic updates (bootc-fetch-apply-updates.timer). After a suspected malicious image, do not rely on bootc rollback alone: audit and remediate persistent /var (including /var/roothome), then re-enroll to a trusted signed image.