CVE-2009-2055 — Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service Vulnerability

Summary

Cisco IOS XR 3.4.0 through 3.8.1 allows remote attackers to cause a denial of service (session reset) via a BGP UPDATE message with an invalid attribute, as demonstrated in the wild on 17 August 2009.

Weakness: CWE-20

Title, description and the vendor's statements are quoted from the CVE record; a vendor's advisory is summarised in Patcharo's words, with a link.

Affected and fixed versions

Per product and release branch, as the vendor's CVE record and official advisory state them. A fixed release is shown only when a document names it: the vendor's, or CERT-FR's for Check Point, with its source.

Remediation

Known exploitation

3% probability of exploitation in the next 30 days (percentile 88%).

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CERT-FR

No CERT-FR advisory or alert of the last two years references this CVE, for the vendors Patcharo covers.

Timeline

1. 19 Aug 2009Published by the source
2. 25 Mar 2022Added to CISA KEV
3. 15 Apr 2022CISA remediation due date
4. 16 Jun 2026Source record last modified
5. 29 Sept 2026EPSS score computed
6. 1 Oct 2026Last verified by Patcharo

Official sources

• Cisco (CVE record)retrieved 1 Oct 2026 at 09:31 UTC
• CISA Known Exploited Vulnerabilitiesretrieved 1 Oct 2026 at 09:28 UTC
• NVDretrieved 27 Sept 2026 at 23:44 UTC
• FIRST EPSSretrieved 30 Sept 2026 at 00:17 UTC

Cisco · CISA Known Exploited Vulnerabilities · NVD · FIRST EPSS