dbcve.org
FreeBSDOperating system

CVE-2025-15547

HIGH · 8.8 CVSS v3.1 Published 2026-03-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
90/100
Remediation priority · Urgent
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In FreeBSD jails with allow.mount.nullfs enabled, a jailed root user can exploit a kernel path lookup limitation to mount directories in a way that escapes the jail's chroot boundary, gaining access to the host or parent jail's full filesystem.

MitigationDisable allow.mount.nullfs in jail configurations unless explicitly required; if needed, apply available FreeBSD security patches or upgrade to a patched version.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FreeBSDOperating system
Affected:= 13.5= 14.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the FreeBSD version
    Run 'uname -r' or check /etc/os-release to get the installed FreeBSD version number
    Affected if The version is 13.5 or 14.3 (these are the affected versions)
  2. Check for running or configured jails
    Run 'jls' to list active jails, or check /etc/jail.conf and /usr/local/etc/jail.conf for jail configurations
    Affected if Any jail exists on the system
  3. Verify allow.mount.nullfs is enabled in jail configurations
    Use 'jls -v' and inspect jail configuration files for the allow.mount.nullfs parameter, or run 'iocage list -a' if iocage is used, and review each jail's configuration for the setting
    Affected if Any jail has 'allow.mount.nullfs' set to 1 or true in its configuration

The environment is affected if running FreeBSD 13.5 or 14.3 AND any jail has allow.mount.nullfs enabled in its configuration, allowing a jailed root user to potentially escape the jail boundary.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Disable allow.mount.nullfs in jail configurations unless explicitly required; if needed, apply available FreeBSD security patches or upgrade to a patched version.

Recommended fix Moderate confidence

FreeBSD 13.5pX or 14.3pX (latest patch level); or upgrade to FreeBSD 14.4 when available

  1. Identify the current FreeBSD version using `freebsd-version -k` or `uname -r`
  2. If running a vulnerable version (13.5 or 14.3), update the FreeBSD base system to the latest patch release for your branch
  3. For FreeBSD 13.x: run `freebsd-update fetch install` and reboot, or upgrade to the latest 13.x stable
  4. For FreeBSD 14.x: run `freebsd-update fetch install` and reboot, or upgrade to the latest 14.x stable
  5. As a configuration mitigation, ensure jail configurations do not set allow.mount.nullfs=1 unless strictly necessary; if nullfs mounts are required, carefully audit which users have jail administrative privileges
  6. After updating, verify the kernel version includes the CVE-2025-15547 fix via `uname -r`
Caveat Kernel update requires system reboot; ensure compatibility of third-party kernel modules with the new kernel version before rebooting

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in FreeBSD Scoped from the published advisory
  • Consultation3.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,800
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,880.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-15547 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-15547 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data