CVE-2026-58099
Memory safety bugs in kqueue copy-on-fork implementation
Description
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.
INFO
Published Date :
Oct. 15, 2026, 7:18 a.m.
Last Modified :
Oct. 15, 2026, 7:18 a.m.
Remotely Exploit :
No
Source :
[email protected]
Solution
- Apply the vendor patch for the kqueue issue.
- Update the affected system software.
- Verify marker knote handling in kqueue operations.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-58099.
| URL | Resource |
|---|---|
| https://security.freebsd.org/advisories/FreeBSD-SA-26:65.kqueue.asc |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-58099 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-58099
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-58099 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-58099 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Oct. 15, 2026
Action Type Old Value New Value Added Description 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. Added CWE CWE-362 Added CWE CWE-416 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/58xxx/CVE-2026-58099.json">CVE-2026-58099</a> Added Reference https://security.freebsd.org/advisories/FreeBSD-SA-26:65.kqueue.asc