CVE-2026-101304: When fdescfs(4) was mounted in a jail with the "nodup" option, opening /dev/fd/N returned a descriptor that di

Routine

HIGH 7.1MITIGATE

CVE-2026-101304 is a high-severity flaw (CVSS 7.1) affecting freebsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.1 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 96%)
CISA exploited list	No
Weakness	CWE-273
Published	2026-10-15
Last modified	2026-10-20

Publisher (CNA): FreeBSD · Vendor: freebsd

Last updated 2026-10-20 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-10-15 07:17 UTCPublished CVE record published
2026-10-20 17:17 UTCUpdated Record last modified

freebsd freebsd MITIGATE

Affected: 14.4 · 14.4 p1 · 14.4 p2 · 14.4 p3 · 14.4 p4 · 14.4 p5 · 14.4 p6 · 14.4 p7

Fixed in: no fixed release known

Safe to downgrade to: a release before 14.4

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-101304?

freebsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-101304 being exploited?

CVE-2026-101304 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-101304 affect?

CVE-2026-101304 affects freebsd. Severity is high (CVSS 7.1). 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 direc

How urgent is CVE-2026-101304?

Priority 26/100. High severity

Related CVEs

CVE-2026-101307 CRITICAL 9.1 MITIGATE When the PCM sample array needs to grow, the RACK stack doubles a 16-bit allocation counter
CVE-2026-101306 CRITICAL 9.8 MITIGATE SCM_RIGHTS file descriptor passing did not preserve FD_RESOLVE_BENEATH when a descriptor was transferred
CVE-2026-101305 HIGH 8.8 MITIGATE renameat(2) did not enforce FD_RESOLVE_BENEATH on its directory arguments
CVE-2026-101303 HIGH 7.5 MITIGATE The IPv6 UDP send path for unconnected sockets did not apply the jail policy of rewriting a loopback destinati
CVE-2026-101302 MEDIUM 6.5 MITIGATE TLS 1.3 embeds the actual record type as the last non-zero byte of the decrypted payload, optionally followed

References

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