The BGP daemon (bgpd) in Quagga 0.99.11 and earlier allows remote attackers to cause a denial of service (crash) via an AS path containing ASN elements whose string representation is longer than expected, which triggers an assert error.
Vender Response
Updated packages are available that bring Quagga to version 0.99.12 which provides numerous bugfixes over the previous 0.99.9 version, and also corrects this issue.