CVE-2009-2055: Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on , 4,601 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 3.3%
EPSS score, percentile 88.5 of all scored records
- How severe?
- 5.9 Medium
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA deadline . Apply updates per vendor instructions.
- Which versions are affected?
Not stated. The CVE record gives vendor and product as “n/a” and the version as “unspecified”.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
What to do
Required action, set by CISA
Apply updates per vendor instructions.
CISA due date for this action: .
Advisories and patches
Linked from CISA's catalog entry
Affected products and versions
The CVE record does not name affected products or versions: vendor and product are “n/a” and the version is “unspecified”.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
About this vulnerability
Cisco IOS XR,when BGP is the configured routing feature, allows remote attackers to cause a denial-of-service (DoS).
Summary: CISA's KEV catalog, as of .
- CISA added CVE-2009-2055 to its Known Exploited Vulnerabilities (KEV) catalog on 25 Mar 2022.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 15 Apr 2022.
- The CVE record was published on 19 Aug 2009, 4,601 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 5.9 (Medium), taken from CISA's enrichment of the record.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 3.3% (percentile 88.5), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.
Description
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
Weakness
- CWE-20: Improper Input Validation
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| Added to CISA KEV | |
| CISA due date for the required action | |
| CVE record last updated |
References
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