Vulnerability · Published Sep 6, 2023 · Assigned by freebsd
CVE-2023-4809pf incorrectly handles multiple IPv6 fragment headers
High 7.5
In plain English
A high-severity security flaw 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 0.8% (higher than 57% of all known vulnerabilities).
Official description
In pf packet processing with a 'scrub fragment reassemble' rule, a packet containing multiple IPv6 fragment headers would be reassembled, and then immediately processed. That is, a packet with multiple fragment extension headers would not be recognized as the correct ultimate payload. Instead a packet with multiple IPv6 fragment headers would unexpectedly be interpreted as a fragmented packet, rather than as whatever the real payload is. As a result, IPv6 fragments may bypass pf firewall rules written on the assumption all fragments have been reassembled and, as a result, be forwarded or processed by the host.
Affected products (as reported)
Weakness: CWE-167
References
- https://security.FreeBSD.org/advisories/FreeBSD-SA-23:10.pf.asc vendor-advisory
- http://www.openwall.com/lists/oss-security/2023/09/08/5
- http://www.openwall.com/lists/oss-security/2023/09/08/6
- http://www.openwall.com/lists/oss-security/2023/09/08/7
- https://security.netapp.com/advisory/ntap-20231221-0009/