Use-after-free in FreeBSD - CVE-2026-45251
Published: May 21, 2026
Vulnerability identifier: #VU132007
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-45251
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: FreeBSD Foundation
Affected software:
FreeBSD
FreeBSD
Detailed vulnerability description
The vulnerability allows a local user to escalate privileges.
The vulnerability exists due to use-after-free in the kernel file descriptor handling code when a file descriptor is closed while a thread is blocked in poll(2) or select(2) waiting on that descriptor. A local user can close a file descriptor during a blocked poll(2) or select(2) operation to escalate privileges.
The issue affects some file descriptor types where blocked threads are not unlinked from the per-object wait queue before the underlying object is freed.
How to mitigate CVE-2026-45251
Install security update from vendor's website.