CVE-2026-45251

Summary

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.

Affected Software

VendorProductVersion RangeStatus
FreeBSDFreeBSD15.0-RELEASE < p9affected
FreeBSDFreeBSD14.4-RELEASE < p5affected
FreeBSDFreeBSD14.3-RELEASE < p14affected

Weaknesses

  • CWE-416: CWE-416: Use After Free

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

References