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.
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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FreeBSD | FreeBSD | unknown |
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Project Subscriptions
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Advisories
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Fixes
Solution
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Workaround
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References
History
Thu, 21 May 2026 10:15:00 +0000
| Type | Values Removed | Values 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. | |
| Title | Kernel use-after-free via file descriptor syscalls | |
| Weaknesses | CWE-416 | |
| References |
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Projects
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MITRE
Status: PUBLISHED
Assigner: freebsd
Published:
Updated: 2026-05-21T09:04:52.569Z
Reserved: 2026-05-11T16:27:44.891Z
Link: CVE-2026-45251
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-05-21T10:16:26.043
Modified: 2026-05-21T10:16:26.043
Link: CVE-2026-45251
Redhat
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OpenCVE Enrichment
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Weaknesses