CVE-2026-45251
Kernel use-after-free via file descriptor syscalls
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.
INFO
Published Date :
May 21, 2026, 10:16 a.m.
Last Modified :
July 23, 2026, 4:10 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update the system kernel to the latest patched version.
- Reboot the system after applying updates.
- Verify the kernel version and patch status.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-45251.
| URL | Resource |
|---|---|
| https://security.freebsd.org/advisories/FreeBSD-SA-26:19.file.asc | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-45251 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-45251
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-45251 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-45251 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Jul. 23, 2026
Action Type Old Value New Value Added Translation Title: FreeBSD, Description: Un descriptor de archivo puede cerrarse mientras un hilo está bloqueado en una llamada a poll(2) o select(2) esperando por ese descriptor. Debido a que el hilo bloqueado no mantiene una referencia al objeto subyacente, este cierre puede resultar en la liberación del objeto mientras el hilo permanece bloqueado. En esta situación, el kernel debe eliminar el hilo bloqueado de la cola de espera por objeto antes de liberar el objeto. En el caso de algunos tipos de descriptores de archivo, el kernel no logró desvincular los hilos bloqueados del objeto antes de liberarlo. Cuando el hilo bloqueado es despertado posteriormente, accede a memoria que ya ha sido liberada resultando en una vulnerabilidad de uso después de liberación. La vulnerabilidad de uso después de liberación puede ser activada por un usuario local sin privilegios y puede ser explotada para obtener privilegios de superusuario. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'FreeBSD', 'modules': ['file'], 'product': 'FreeBSD', 'versions': [{'status': 'affected', 'version': '15.0-RELEASE', 'lessThan': 'p9', 'versionType': 'release'}, {'status': 'affected', 'version': '14.4-RELEASE', 'lessThan': 'p5', 'versionType': 'release'}, {'status': 'affected', 'version': '14.3-RELEASE', 'lessThan': 'p14', 'versionType': 'release'}], 'defaultStatus': 'unknown'}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-45251', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-05-21T00:00:00+00:00'} -
Initial Analysis by [email protected]
May. 21, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p5:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p6:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p7:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p8:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p9:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p11:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p5:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p6:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p12:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p13:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p7:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p8:*:*:*:*:*:* Added Reference Type FreeBSD: https://security.freebsd.org/advisories/FreeBSD-SA-26:19.file.asc Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 21, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H -
New CVE Received by [email protected]
May. 21, 2026
Action Type Old Value New Value Added 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. Added CWE CWE-416 Added Reference https://security.freebsd.org/advisories/FreeBSD-SA-26:19.file.asc