High severity · published Oct 15, 2026
CVE-2026-101304
Multiple jail filesystem root escapes
7.1
CVSS
0.1%
EPSS
No
On KEV
Description
When fdescfs(4) was mounted in a jail with the "nodup" option, opening /dev/fd/N returned a descriptor that did not inherit FD_RESOLVE_BENEATH or the Capsicum capability rights of descriptor N.
A process in a jail that has received a directory file descriptor from another jail can use these techniques to escape the jail's filesystem root restriction.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 4% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FR
FreeBSD · FreeBSD
15.1-RELEASE before p4; 15.0-RELEASE before p14; 14.5-RELEASE before p1; 14.4-RELEASE before p10 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-101304
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-101304
Patch
https://security.freebsd.org/advisories/FreeBSD-SA-26:66.jail.asc
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