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Linux Distros Unpatched Vulnerability : CVE-2026-49943

medium Nessus Plugin ID 318357

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

 - 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. (CVE-2026-49943)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

See Also

https://security-tracker.debian.org/tracker/CVE-2026-49943

Plugin Details

Severity: Medium

ID: 318357

File Name: unpatched_CVE_2026_49943.nasl

Version: 1.2

Type: Local

Agent: unix

Family: Misc.

Published: 6/3/2026

Updated: 6/3/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.2

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 4.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2026-49943

CVSS v3

Risk Factor: Medium

Base Score: 6.3

Temporal Score: 6

Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:P/RL:U/RC:C

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:11.0, p-cpe:/a:debian:debian_linux:bird, p-cpe:/a:debian:debian_linux:bird2, cpe:/o:debian:debian_linux:14.0, p-cpe:/a:debian:debian_linux:bird3, cpe:/o:debian:debian_linux:12.0, cpe:/o:debian:debian_linux:13.0

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 6/2/2026

Reference Information

CVE: CVE-2026-49943