---
id: CVE-2026-58099
title: >-
  When copying knotes from a parent kqueue to a child, the copy code did not
  correctly exclude marker knotes (used internally to track list traversal
  position) before marking them as in-flux and releasing the kqueue lock
summary: >-
  When copying knotes from a parent kqueue to a child, the copy code did not
  correctly exclude marker knotes (used internally to track list traversal
  position) before marking them as in-flux and releasing the kqueue lock.  If
  another threa…
severity: none
cwe:
  - CWE-362
  - CWE-416
vendor: FreeBSD
product: FreeBSD
affected:
  - FreeBSD >= 15.1-RELEASE < p4
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T07:18:02.373'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-58099'
references:
  - url: 'https://security.freebsd.org/advisories/FreeBSD-SA-26:65.kqueue.asc'
    label: secteam@freebsd.org
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-15T06:56:27.296Z'
---

## Overview

When copying knotes from a parent kqueue to a child, the copy code did not correctly exclude marker knotes (used internally to track list traversal position) before marking them as in-flux and releasing the kqueue lock.  If another thread freed a marker while the lock was dropped, the subsequent in-flux decrement operated on freed memory.

An unprivileged local user may be able to exploit these races to escalate privileges.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.