An issue was discovered in bgpd in FRRouting (FRR) through 8.4. By crafting a BGP OPEN message with an option of type 0xff (Extended Length from RFC 9072), attackers may cause a denial of service (assertion failure and daemon restart, or out-of-bounds read). This is possible because of inconsistent boundary checks that do not account for reading 3 bytes (instead of 2) in this 0xff case.
https://www.debian.org/security/2023/dsa-5495
https://lists.debian.org/debian-lts-announce/2023/09/msg00020.html