Vulnerability in CZ.NIC BIRD Internet Routing Daemon (CVE-2026-49943)
Summary
Vulnerability in CZ.NIC BIRD Internet Routing Daemon (CVE-2026-49943). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
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.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49943 has been found in CZ.NIC BIRD Internet Routing Daemon.
Risk of unauthorized operations or information disclosure. CVSS score: 6.3/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CZ.NIC BIRD Internet Routing Daemon CVE-2026-49943" on the vendor's site.
CVE-2026-49943 (CZ.NIC BIRD Internet Routing Daemon) — CWE-121 / CVSS v3 6.3
Attack vector: remote (network-reachable) / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-121) exists in CZ.NIC BIRD Internet Routing Daemon.
Check the vendor advisory for the affected versions of CZ.NIC BIRD Internet Routing Daemon.
Severity: Medium (CVSS 6.3/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで CZ.NIC BIRD Internet Routing Daemon を使っているサービスとバージョンを洗い出す。
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2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-49943 bird
- Ubuntu UBUNTU-CVE-2026-49943 bird
References
- advisory nvd.nist.gov
- advisory github.com
- web bird.nic.cz
- web gitlab.nic.cz
- web github.com