container escape due to /dev/console mount and related races

Vulnerability Description

runc is a CLI tool for spawning and running containers according to the OCI specification. 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/$n` to `/dev/console` inside the container, an attacker can trick runc into bind-mounting paths which would normally be made read-only or be masked onto a path that the attacker can write to. This attack is very similar in concept and application to CVE-2025-31133, except that it attacks a similar vulnerability in a different target (namely, the bind-mount of `/dev/pts/$n` to `/dev/console` as configured for all containers that allocate a console). This happens after `pivot_root(2)`, so this cannot be used to write to host files directly -- however, as with CVE-2025-31133, this can load to denial of service 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` (respectively). This issue is fixed in versions 1.2.8, 1.3.3 and 1.4.0-rc.3.

References

• https://github.com/opencontainers/runc/security/advisories/GHSA-qw9x-cqr3-wc7r
• https://github.com/opencontainers/runc/commit/01de9d65dc72f67b256ef03f9bfb795a2bf143b4
• https://github.com/opencontainers/runc/commit/398955bccb7f20565c224a3064d331c19e422398
• https://github.com/opencontainers/runc/commit/531ef794e4ecd628006a865ad334a048ee2b4b2e
• https://github.com/opencontainers/runc/commit/9be1dbf4ac67d9840a043ebd2df5c68f36705d1d
• https://github.com/opencontainers/runc/commit/aee7d3fe355dd02939d44155e308ea0052e0d53a
• https://github.com/opencontainers/runc/commit/db19bbed5348847da433faa9d69e9f90192bfa64
• https://github.com/opencontainers/runc/commit/de87203e625cd7a27141fb5f2ad00a320c69c5e8
• https://github.com/opencontainers/runc/commit/ff94f9991bd32076c871ef0ad8bc1b763458e480