CVE catalog

CVE-2026-49943

Severity: Medium · CVSS 6.3
Published: Jun 2, 2026, 4:16:52 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.30% · Oct 25, 2026

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 fixed stack buffer, resulting in a crash of the daemon. NOTE: reportedly, the Supplier's position is that a fix is not being prioritized because all network operators should already be rejecting routes with unusually long attributes.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	bird	bookworm	`1.6.8-2.1`	vulnerable
Debian	bird2	sid	`2.20.0-1`	vulnerable
Debian	bird2	forky	`2.20.0-1`	vulnerable
Debian	bird2	trixie	`2.17.5-0+deb13u1`	vulnerable
Debian	bird2	trixie-security	`2.17.5-0+deb13u1`	vulnerable
Debian	bird2	bookworm	`2.0.12-7`	vulnerable
Cpe	bird	Not reported	Not reported	vulnerable
Cpe	bird2	Not reported	Not reported	vulnerable

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	bird	source	bookworm	`(unfixed)`	unimportant	Not reported	Not reported
Debian	bird2	source	sid	`(unfixed)`	unimportant	Not reported	Not reported
Debian	bird2	source	forky	`(unfixed)`	unimportant	Not reported	Not reported
Debian	bird2	source	trixie	`(unfixed)`	unimportant	Not reported	Not reported
Debian	bird2	source	bookworm	`(unfixed)`	unimportant	Not reported	Not reported

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[bird]Affected
Source package: [bird]
Details (2)
- 1.6.8-2.1+b1 · amd64 · bookworm
  Affected
  nvd · bird · debian · bookworm; nvd · bird · debian · 12
- 1.6.8-2.1+b1 · arm64 · bookworm
  Affected
  nvd · bird · debian · bookworm; nvd · bird · debian · 12
[bird2]Affected
Details (2)
- 2.0.12-7 · amd64 · bookworm
  Affected
  nvd · bird2 · debian · bookworm; nvd · bird2 · debian · 12
- 2.0.12-7 · arm64 · bookworm
  Affected
  nvd · bird2 · debian · bookworm; nvd · bird2 · debian · 12
[bird2-doc]Affected
Source package: [bird2]
Details (2)
- 2.0.12-7 · all · bookworm
  Affected
  nvd · bird2 · debian · bookworm; nvd · bird2 · debian · 12
- 2.0.12-7 · all · bookworm
  Affected
  nvd · bird2 · debian · bookworm; nvd · bird2 · debian · 12
[bird-bgp]Affected
Source package: [bird]
Details (2)
- 1.6.8-2.1 · all · bookworm
  Affected
  nvd · bird · debian · bookworm; nvd · bird · debian · 12
- 1.6.8-2.1 · all · bookworm
  Affected
  nvd · bird · debian · bookworm; nvd · bird · debian · 12
[bird-doc]Affected
Source package: [bird]
Details (2)
- 1.6.8-2.1 · all · bookworm
  Affected
  nvd · bird · debian · bookworm; nvd · bird · debian · 12
- 1.6.8-2.1 · all · bookworm
  Affected
  nvd · bird · debian · bookworm; nvd · bird · debian · 12

[Debian 13 (Trixie)]

[bird2]Affected
Details (4)
- 2.17.5-0+deb13u1 · amd64 · trixie
  Affected
  nvd · bird2 · debian · 13
- 2.17.5-0+deb13u1 · arm64 · trixie
  Affected
  nvd · bird2 · debian · 13
- 2.17.5-0+deb13u1 · amd64 · trixie-security
  Affected
  nvd · bird2 · debian · 13
- 2.17.5-0+deb13u1 · arm64 · trixie-security
  Affected
  nvd · bird2 · debian · 13
[bird2-doc]Affected
Source package: [bird2]
Details (4)
- 2.17.5-0+deb13u1 · all · trixie
  Affected
  nvd · bird2 · debian · 13
- 2.17.5-0+deb13u1 · all · trixie
  Affected
  nvd · bird2 · debian · 13
- 2.17.5-0+deb13u1 · all · trixie-security
  Affected
  nvd · bird2 · debian · 13
- 2.17.5-0+deb13u1 · all · trixie-security
  Affected
  nvd · bird2 · debian · 13
[bird3]Affected
Details (6)
- 3.1.7-0+deb13u1 · amd64 · trixie
  Affected
  nvd · bird3 · debian · 13
- 3.1.7-0+deb13u1 · arm64 · trixie
  Affected
  nvd · bird3 · debian · 13
- 3.3.2-1~bpo13+1 · amd64 · trixie-backports
  Affected
  nvd · bird3 · debian · 13
- 3.3.2-1~bpo13+1 · arm64 · trixie-backports
  Affected
  nvd · bird3 · debian · 13
- 3.1.7-0+deb13u1 · amd64 · trixie-security
  Affected
  nvd · bird3 · debian · 13
- 3.1.7-0+deb13u1 · arm64 · trixie-security
  Affected
  nvd · bird3 · debian · 13
[bird3-doc]Affected
Source package: [bird3]
Details (6)
- 3.1.7-0+deb13u1 · all · trixie
  Affected
  nvd · bird3 · debian · 13
- 3.1.7-0+deb13u1 · all · trixie
  Affected
  nvd · bird3 · debian · 13
- 3.3.2-1~bpo13+1 · all · trixie-backports
  Affected
  nvd · bird3 · debian · 13
- 3.3.2-1~bpo13+1 · all · trixie-backports
  Affected
  nvd · bird3 · debian · 13
- 3.1.7-0+deb13u1 · all · trixie-security
  Affected
  nvd · bird3 · debian · 13
- 3.1.7-0+deb13u1 · all · trixie-security
  Affected
  nvd · bird3 · debian · 13

Observed: Oct 27, 2026, 7:18:46 AM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]