CVE-2026-45251 | Kernel use-after-free via file descriptor syscalls

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.

Published: 2026-05-21 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-45251 is rated Low Risk (32.6/100): CVSS High severity, with low exploitation likelihood (EPSS 0.14%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-45251

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.02% 0.14% +0.12%
2 2026-05-21 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-45251

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-45251

GitHub Security Advisory for CVE-2026-45251

GHSA-wp9w-fp98-2cxm · Severity: high — A file descriptor can be closed while a thread is blocked in a poll(2) or select(2) call waiting...

Affected software / configurations for CVE-2026-45251

Vendor Product Version Raw CPE
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p11:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p12:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p13:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p2:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p3:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p4:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p5:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p6:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p7:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p8:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p9:*:*:*:*:*:*
freebsd freebsd 14.4 cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:*
freebsd freebsd 14.4 cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:*
freebsd freebsd 14.4 cpe:2.3:o:freebsd:freebsd:14.4:p2:*:*:*:*:*:*
freebsd freebsd 14.4 cpe:2.3:o:freebsd:freebsd:14.4:p3:*:*:*:*:*:*
freebsd freebsd 14.4 cpe:2.3:o:freebsd:freebsd:14.4:p4:*:*:*:*:*:*
freebsd freebsd 14.4 cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p3:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p4:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p5:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p6:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p7:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p8:*:*:*:*:*:*

References for CVE-2026-45251

cvelogic Threat Intelligence