Vulnerability · Published Aug 19, 2026 · Assigned by freebsd

CVE-2026-49421unlinkat(2) ignores AT_RESOLVE_BENEATH flag

High 7.1

In plain English

A high-severity security flaw in FreeBSD from FreeBSD. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities).

Severity (CVSS 3.1)7.1High

Exploit odds (30 days)0.1%top 97.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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 containment may delete files outside the intended directory tree.

Affected products (as reported)

Vendor	Product	Versions
FreeBSD	FreeBSD	15.1-RELEASE – before p115.0-RELEASE – before p1114.4-RELEASE – before p714.3-RELEASE – before p16

Weakness: CWE-273 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

References

https://security.freebsd.org/advisories/FreeBSD-SA-26:42.unlinkat.asc vendor-advisory