bird2 vulnerabilities

CVE-2026-112112

An IPv6 FlowSpec validation bypass in the CZ.NIC BIRD Internet Routing Daemon allows an established BGP peer to inject FlowSpec rules matching destinations outside the address space authorized by the unicast-route validation procedure. With validation enabled on the receiving flow6 channel, BIRD fails to reject a destination prefix component with a nonzero offset, contrary to RFC 8956 section 5. It validates a reconstructed prefix with zero-filled skipped bits, although the original FlowSpec component can match a broader set of IPv6 addresses. Given a suitable unicast route from the peer, the rule can pass validation and, where export policy

CVE-2026-49943

CZ.NIC BIRD Internet Routing Daemon through 2.19.0 contains a stack-based buffer overflow in the BGP AS_PATH mask matching implementation in nest/a-path.c. The as_path_match() function uses a fixed-size stack array of 2048 + 1 pm_pos entries, while parse_path() expands AS_PATH segments from a received BGP UPDATE without enforcing a corresponding capacity limit. When RFC 8654 BGP Extended Messages are enabled and a BIRD filter evaluates an AS path mask expression such as "bgp_path ~ [= ... =]", an established BGP peer can send a long AS_PATH containing more than 2048 expanded ASNs. This causes parse_path()/as_path_match() to write beyond the f

CVE-2019-16159

BIRD Internet Routing Daemon 1.6.x through 1.6.7 and 2.x through 2.0.5 has a stack-based buffer overflow. The BGP daemon's support for RFC 8203 administrative shutdown communication messages included an incorrect logical expression when checking the validity of an input message. Sending a shutdown communication with a sufficient message length causes a four-byte overflow to occur while processing the message, where two of the overflow bytes are attacker-controlled and two are fixed.

• Update to 2.0.6-1