The GETALL and SETALL commands in semctl(2) recorded the number of semaphores in the target set, dropped the lock protecting the set, allocated a buffer sized for that count, and reacquired the lock. A sequence-number check was used to verify that the set had not been replaced in the interim, but the sequence number wraps after 0x8000 create/destroy cycles. By rapidly destroying and recreating semaphore sets at the same index, another process can cause the sequence number to wrap, allowing a set with a different number of semaphores to pass validation. The subsequent copy then reads or writes past the end of the allocated buffer.
An unprivileged local user can trigger out-of-bounds reads and writes on kernel heap memory, potentially leading to privilege escalation.
An unprivileged local user can trigger out-of-bounds reads and writes on kernel heap memory, potentially leading to privilege escalation.
Metrics
Affected Vendors & Products
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Advisories
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Fixes
Solution
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Workaround
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References
History
Wed, 19 Aug 2026 08:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | The GETALL and SETALL commands in semctl(2) recorded the number of semaphores in the target set, dropped the lock protecting the set, allocated a buffer sized for that count, and reacquired the lock. A sequence-number check was used to verify that the set had not been replaced in the interim, but the sequence number wraps after 0x8000 create/destroy cycles. By rapidly destroying and recreating semaphore sets at the same index, another process can cause the sequence number to wrap, allowing a set with a different number of semaphores to pass validation. The subsequent copy then reads or writes past the end of the allocated buffer. An unprivileged local user can trigger out-of-bounds reads and writes on kernel heap memory, potentially leading to privilege escalation. | |
| Title | Heap out-of-bounds access in semctl(2) | |
| Weaknesses | CWE-125 CWE-191 CWE-787 |
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| References |
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Projects
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MITRE
Status: PUBLISHED
Assigner: freebsd
Published:
Updated: 2026-08-19T07:47:50.665Z
Reserved: 2026-06-29T01:40:17.498Z
Link: CVE-2026-58087
Vulnrichment
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NVD
Status : Received
Published: 2026-08-19T08:17:12.877
Modified: 2026-08-19T08:17:12.877
Link: CVE-2026-58087
Redhat
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OpenCVE Enrichment
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