---
id: CVE-2026-101304
title: >-
  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 di…
summary: >-
  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 di…
severity: none
cwe:
  - CWE-273
vendor: FreeBSD
product: FreeBSD
affected:
  - FreeBSD >= 15.1-RELEASE < p4
  - FreeBSD >= 15.0-RELEASE < p14
  - FreeBSD >= 14.5-RELEASE < p1
  - FreeBSD >= 14.4-RELEASE < p10
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T07:17:57.550'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-101304'
references:
  - url: 'https://security.freebsd.org/advisories/FreeBSD-SA-26:66.jail.asc'
    label: secteam@freebsd.org
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-15T07:57:27.842Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.