Race Condition Enabling Link Following Affecting github.com/opencontainers/runc/libcontainer package, versions <1.2.8>=1.3.0-rc.1 <1.3.3>=1.4.0-rc.1 <1.4.0-rc.3

github.com/opencontainers/runc/libcontainer is a package for a modern container runtime.

Affected versions of this package are vulnerable to Race Condition Enabling Link Following via a race condition in the maskedPaths feature. An attacker can gain unauthorized access to host files, execute arbitrary code with elevated privileges, or cause a denial of service by manipulating the /dev/null inode or replacing it with a symlink to an attacker-controlled path during container creation. This allows bind-mounting arbitrary files to path inside the container, or bypassing intended masking protections, potentially exposing sensitive host information or enabling container escape.

Note:

This is only exploitable if the attacker can influence the container's /dev/null prior to the bind-mount operation or trigger parallel container executions with shared mounts.

1. Using user namespaces for containers.

2. Configuring containers to avoid root privileges.

3. Applying restrictive AppArmor profiles.

4. Avoiding untrusted container images.

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