CVE-2023-6534: Freebsd

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

In versions of FreeBSD 14.0-RELEASE before 14-RELEASE-p2, FreeBSD 13.2-RELEASE before 13.2-RELEASE-p7 and FreeBSD 12.4-RELEASE before 12.4-RELEASE-p9, the pf(4) packet filter incorrectly validates TCP sequence numbers.  This could allow a malicious actor to execute a denial-of-service attack against hosts behind the firewall.

Affected products

• Freebsd Freebsd: version 12.4 only; version 13.2 only; version 14.0 only

Published 2023-12-13. Last modified 2026-06-17.