MNBSD-2026-1: Jail chroot escape via fd exchange with a different jail

Severity: Unknown

Affected Package: kernel

Summary: Jail chroot escape via fd exchange with a different jail

Description

In a configuration where processes in two different jails are able to exchange file descriptors using a Unix domain socket, it is possible for a jailed process to receive a directory for a descriptor that is below that process' jail root. This enables full filesystem access for a jailed process, breaking the chroot. Note that the system administrator is still responsible for ensuring that an unprivileged user on the jail host is not able to pass directory descriptors to a jailed process, even in a patched kernel.

Affected Versions

kernel

Recommendations

No specific recommendations provided.

References

Additional Information

Aliases: CVE-2025-15576

Published: March 16, 2026
Last Modified: March 16, 2026