The BGP implementation in bgpd in Quagga before 0.99.20.1 does not properly use message buffers for OPEN messages, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a message associated with a malformed Four-octet AS Number Capability (aka AS4 capability).
rhn.redhat.com/errata/RHSA-2012-1259.html
secunia.com/advisories/48949
www.debian.org/security/2012/dsa-2459
www.kb.cert.org/vuls/id/551715
lists.fedoraproject.org/pipermail/package-announce/2012-April/078794.html
lists.fedoraproject.org/pipermail/package-announce/2012-April/078910.html
lists.fedoraproject.org/pipermail/package-announce/2012-April/078926.html