By default, jailed processes cannot mount filesystems, including nullfs(4). However, the allow.mount.nullfs option enables mounting nullfs filesystems, subject to privilege checks.
If a privileged user within a jail is able to nullfs-mount directories, a limitation of the kernel's path lookup logic allows that user to escape the jail's chroot, yielding access to the full filesystem of the host or parent jail.
In a jail configured to allow nullfs(4) mounts from within the jail, the jailed root user can escape the jail's filesystem root.
If a privileged user within a jail is able to nullfs-mount directories, a limitation of the kernel's path lookup logic allows that user to escape the jail's chroot, yielding access to the full filesystem of the host or parent jail.
In a jail configured to allow nullfs(4) mounts from within the jail, the jailed root user can escape the jail's filesystem root.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FreeBSD | FreeBSD | unknown |
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Fixes
Solution
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Workaround
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References
History
Mon, 09 Mar 2026 12:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | By default, jailed processes cannot mount filesystems, including nullfs(4). However, the allow.mount.nullfs option enables mounting nullfs filesystems, subject to privilege checks. If a privileged user within a jail is able to nullfs-mount directories, a limitation of the kernel's path lookup logic allows that user to escape the jail's chroot, yielding access to the full filesystem of the host or parent jail. In a jail configured to allow nullfs(4) mounts from within the jail, the jailed root user can escape the jail's filesystem root. | |
| Title | Jail escape by a privileged user via nullfs | |
| Weaknesses | CWE-269 | |
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: freebsd
Published:
Updated: 2026-03-09T11:46:51.973Z
Reserved: 2026-01-26T15:57:03.264Z
Link: CVE-2025-15547
Vulnrichment
No data.
NVD
Status : Awaiting Analysis
Published: 2026-03-09T12:16:11.403
Modified: 2026-03-09T13:35:07.393
Link: CVE-2025-15547
Redhat
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OpenCVE Enrichment
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Weaknesses