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Vulnerabilities

Vulnerability · CVE-2026-45251

A file descriptor can be closed while a thread is blocked in a poll(2) or select(2) call waiting for that descriptor.

Published May 21, 2026 · catalog updated Jul 23, 2026 · A file descriptor can

Check if you run it

No confirmed exploitation is on record for CVE-2026-45251. EPSS is 0.15%. Act only if a listed version of A file descriptor can is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A file descriptor can).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.15%
Remediation
Advisory link
Affected products
cpe freebsd/freebsd

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe freebsd/freebsd14.3

How to fix CVE-2026-45251

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-45251. EPSS is 0.15%. Act only if a listed version of A file descriptor can is installed.

Which versions are affected?

Compare what you have installed with 14.3. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-416: Use After Free. EPSS 0.15%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 21, 2026 · NIST NVD

    Detected

    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

  2. Jul 23, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-45251

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-45251

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-2026-45251

    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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.