Skip to main content
VulnerabilityPublished

CVE-2026-49943: NIC BIRD · Stack-based Buffer Overflow

Affects NIC BIRDSource CVE Database V5

0
Compare

Not known to be exploited · CVSS 6.3 Medium.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
NICBIRDAffected
  • <=2.19.0
Fixed in–

AI-suggested

The vendor advises that network operators should reject routes with unusually long AS_PATH attributes to prevent exploitation. Operators should implement route filtering policies to block excessively long AS_PATHs as a mitigation measure.

Description

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.

References

Community reviews

Loading reviews…