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Vulnerability · Published Aug 19, 2026 · Assigned by freebsd

CVE-2026-49422Use-after-free in TCP RACK stack option handler

High 8.4

In plain English

A high-severity use-after-free in FreeBSD from FreeBSD. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities).

Severity (CVSS 3.1)8.4High
Exploit odds (30 days)0.2%top 93.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

The RACK setsockopt(2) handler drops the connection lock in order to copy option data from userspace, then reacquires the lock. After reacquiring, it verifies that the TCP stack had not been switched away, but did not reload its pointer to the stack's per-connection control block. If userspace switches stacks twice during this window, the check will succeed but the saved pointer will refer to freed memory. The bug may be exploitable by an unprivileged local user to escalate privileges.

Affected products (as reported)

VendorProductVersions
FreeBSD FreeBSD 15.1-RELEASE – before p115.0-RELEASE – before p1114.4-RELEASE – before p714.3-RELEASE – before p16

Weakness: CWE-416 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References