A Buffer Over-read vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). When an affected device receives a BGP update with a set of specific optional transitive attributes over an established peering session, rpd will crash and restart when attempting to advertise the received information to another peer. This issue can only happen if one or both of the BGP peers of the receiving session are non-4-byte-AS capable as determined from the advertised capabilities during BGP session establishment.

Junos OS and Junos OS Evolved default behavior is 4-byte-AS capable unless this has been specifically disabled by configuring: [ protocols bgp ... disable-4byte-as ] Established BGP sessions can be checked by executing: show bgp neighbor <IP address> | match "4 byte AS" This issue affects: Junos OS: all versions before 22.4R3-S8, 23.2 versions before 23.2R2-S5, 23.4 versions before 23.4R2-S6, 24.2 versions before 24.2R2-S2, 24.4 versions before 24.4R2; Junos OS Evolved: all versions before 22.4R3-S8-EVO, 23.2 versions before 23.2R2-S5-EVO, 23.4 versions before 23.4R2-S6-EVO, 24.2 versions before 24.2R2-S2-EVO, 24.4 versions before 24.4R2-EVO.