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Fencer Vulns
high 7.5

CVE-2025-15576 json

Jail chroot escape via fd exchange with a different jail

published 2026-03-09 8 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-208409

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

If two sibling jails are restricted to separate filesystem trees, which is to say that neither of the two jail root directories is an ancestor of the other, jailed processes may nonetheless be able to access a shared directory via a nullfs mount, if the administrator has configured one.

In this case, cooperating processes in the two jails may establish a connection using a unix domain socket and exchange directory descriptors with each other.

When performing a filesystem name lookup, at each step of the lookup, the kernel checks whether the lookup would descend below the jail root of the current process. If the jail root directory is not encountered, the lookup continues.

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.

Patch / fix

  • FreeBSD FreeBSD p9, p10

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
8 mo ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
NVD 3.1 7.5 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
CNA 3.1 7.5 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N

Affected products

  • FreeBSD FreeBSD

Classification

Weakness
  • CWE-269 Improper Privilege Management
  • CWE-488 Exposure of Data Element to Wrong Session
  • CWE-790 Improper Filtering of Special Elements

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.