CVE-2026-49421: The kernel function that implements unlinkat(2) and funlinkat(2) validated the AT_RESOLVE_BENEATH flag but fai

Routine

HIGH 7.1MITIGATE

CVE-2026-49421 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.

The kernel function that implements unlinkat(2) and funlinkat(2) validated the AT_RESOLVE_BENEATH flag but failed to pass it through to the underlying path lookup. The flag was silently dropped, so path resolution was not actually restricted. A process that uses AT_RESOLVE_BENEATH with unlinkat(2) or funlinkat(2) to confine path resolution can in fact resolve paths above the starting directory. A caller relying on this flag for path containmen

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 97%)
CISA exploited list	No
Weakness	CWE-273
Published	2026-08-19
Last modified	2026-09-01

Publisher (CNA): FreeBSD · Vendor: freebsd

Last updated 2026-09-01 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-19 06:17 UTCPublished CVE record published
2026-09-01 20:20 UTCUpdated Record last modified

freebsd freebsd MITIGATE

Affected: 14.3 · 14.3 p1 · 14.3 p10 · 14.3 p11 · 14.3 p12 · 14.3 p13 · 14.3 p14 · 14.3 p15

Fixed in: no fixed release known

Safe to downgrade to: a release before 14.3

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-2026-49421?

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

Is CVE-2026-49421 being exploited?

CVE-2026-49421 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-2026-49421 affect?

CVE-2026-49421 affects freebsd. Severity is high (CVSS 7.1). The kernel function that implements unlinkat(2) and funlinkat(2) validated the AT_RESOLVE_BENEATH flag but failed to pass it through to the underlying path lookup. The flag was silently dropped, so path resolution was not actually restrict

How urgent is CVE-2026-49421?

Priority 26/100. High severity

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References

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