CVE-2023-4809

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.

Date published : 2023-09-06

https://security.FreeBSD.org/advisories/FreeBSD-SA-23:10.pf.asc

http://www.openwall.com/lists/oss-security/2023/09/08/5