UNIX Symbolic Link (Symlink) Following

Summary

runc is a CLI tool for spawning and running containers according to the OCI specification. In versions 1.0.0-rc3 through 1.2.7, 1.3.0-rc.1 through 1.3.2, and 1.4.0-rc.1 through 1.4.0-rc.2, due to insufficient checks when bind-mounting "/dev/pts/$n" to "/dev/console" inside the container, an attacker can trick runc into bind-mounting paths that would normally be made read-only or be masked onto a path that the attacker can write to. This attack is very similar in concept and application to CVE-2025-31133, except that it targets a similar vulnerability in a different component (namely, the bind-mount of "/dev/pts/$n" to "/dev/console" as configured for all containers that allocate a console). This happens after "pivot_root(2)", so it cannot be used to write to host files directly -- however, as with CVE-2025-31133, this can lead to Denial-of-Service (DoS) of the host or a container breakout by providing the attacker with a writable copy of "/proc/sysrq-trigger" or "/proc/sys/kernel/core_pattern".