CVE-2023-6534: TCP spoofing vulnerability in pf(4)

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-12-13 · updated 2026-06-17

Description

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: 12.4, 12.4-p1, 12.4-p2, 12.4-p3, 12.4-p4, 12.4-p5 (+17)

References

https://security.freebsd.org/advisories/FreeBSD-SA-23:17.pf.asc
https://security.netapp.com/advisory/ntap-20240112-0007/
https://security.freebsd.org/advisories/FreeBSD-SA-23:17.pf.asc
https://security.netapp.com/advisory/ntap-20240112-0007/

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