Description
While the kernel was copying knotes during fork, a knote with a timer-based filter could fire and be enqueued on the kqueue's active list before the copy was complete. The copy routine did not account for this and could enqueue the new knote a second time, corrupting the active list. In addition, the copy routine did not hold the appropriate locks while reading knote state, allowing further races.

An unprivileged local user can trigger a use-after-free in the kernel, potentially leading to privilege escalation.
Published: 2026-08-19
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Wed, 19 Aug 2026 07:45:00 +0000

Type Values Removed Values Added
Description While the kernel was copying knotes during fork, a knote with a timer-based filter could fire and be enqueued on the kqueue's active list before the copy was complete. The copy routine did not account for this and could enqueue the new knote a second time, corrupting the active list. In addition, the copy routine did not hold the appropriate locks while reading knote state, allowing further races. An unprivileged local user can trigger a use-after-free in the kernel, potentially leading to privilege escalation.
Title Use-after-free in kqueue copy-on-fork
Weaknesses CWE-416
References

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cve-icon MITRE

Status: PUBLISHED

Assigner: freebsd

Published:

Updated: 2026-08-19T07:33:21.096Z

Reserved: 2026-06-29T01:40:17.498Z

Link: CVE-2026-58083

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-19T08:17:12.470

Modified: 2026-08-19T08:17:12.470

Link: CVE-2026-58083

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses