CVE-2026-45251 Details
Description
A file descriptor can be closed while a thread is blocked in a poll(2) or select(2) call waiting for that descriptor. Because the blocked thread does not hold a reference to the underlying object, this closure may result in the object being freed while the thread remains blocked. In this situation, the kernel must remove the blocked thread from the per-object wait queue prior to freeing the object. In the case of some file descriptor types, the kernel failed to unlink blocked threads from the object before freeing it. When the blocked thread is subsequently woken, it accesses memory that has already been freed resulting in a use-after-free vulnerability. The use-after-free vulnerability may be triggered by an unprivileged local user and can be exploited to obtain superuser privileges.
A use-after-free vulnerability has been identified in the FreeBSD kernel, affecting all supported versions. The issue arises when a file descriptor is closed while a thread is blocked in a poll or select call waiting for that descriptor. The blocked thread does not maintain a reference to the underlying object, which can lead to the object being freed while the thread remains blocked. If this occurs, the kernel must unlink the blocked thread from the wait queue before freeing the object. However, for certain file descriptor types, the kernel failed to do so. When the blocked thread is awakened, it accesses memory that has already been freed, creating a use-after-free scenario. This vulnerability can be exploited by an unprivileged local user to gain superuser privileges.
Users can upgrade to a supported FreeBSD stable or release branch dated after the correction date and reboot the system. Instructions for updating via the pkg utility, freebsd-update utility, or by applying a source code patch are available in the FreeBSD Security Advisory.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed May 21, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://security.freebsd.org/advisories/FreeBSD-SA-26:19.file.asc | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-416 | Use After Free | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| freebsd freebsd | 14.3 - 14.3 p1 14.3 p10 14.3 p11 14.3 p12 14.3 p13 14.3 p2 14.3 p3 14.3 p4 14.3 p5 14.3 p6 14.3 p7 14.3 p8 14.3 p9 14.4 - 14.4 p1 14.4 p2 14.4 p3 14.4 p4 14.4 rc1 15.0 - 15.0 p1 15.0 p2 15.0 p3 15.0 p4 15.0 p5 15.0 p6 15.0 p7 15.0 p8 |
CPE
Remediation
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Change History
6 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 23, 2026 | CVE Translated | [email protected] |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 21, 2026 | Initial Analysis | [email protected] |
| May 21, 2026 | CVE Modified | CISA-ADP |
| May 21, 2026 | New CVE Received | [email protected] |