CVE-2009-2055

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.

CVSS: 5.9Mediumscored by CISA
Exploited in the wild: Yes, in CISA KEV since 25 Mar 2022CISA deadline for US federal agencies: 15 Apr 2022
EPSS: 3.3%chance of exploitation in the next 30 daystop 12% of scored CVEsFIRST score of 11 Nov 2026
Fix: Patch availablesee the advisories in the references
Published: 19 Aug 2009analysed here 12 Nov 2026

Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)

Summary

Triage

Exploitable: At runtime
Attack vector: network
Weakness: CWE-20 Improper Input Validation
Can a WAF block it?: Partly. See why

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Products named in our analysis

cisco:ios_xr

Fix and mitigation

WAF and other mitigations

Can a WAF block it? Partly. The bug can be reached over the network, so generic WAF rules may stop some attacks. Its weakness type is unknown, so we cannot be more precise.

Also consider: patch

Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Listed since 25 Mar 2022.
CISA due date: 15 Apr 2022, the remediation deadline for US federal agencies
CISA required action: Apply updates per vendor instructions.
Public exploit code: None on record in Exploit-DB, Metasploit, Nuclei templates or PoC-in-GitHub.
CISA SSVC: exploitation active, automatable no, technical impact partialAssessed by CISA 8 Nov 2024 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.

Timeline

19 Aug 2009Published
25 Mar 2022Added to CISA KEV (exploited in the wild)4,600 days (about 13 years) later
15 Apr 2022CISA remediation due date (US federal agencies)21 days later
8 Nov 2024CISA SSVC assessment: exploitation active939 days (about 3 years) later
12 Jan 2026CVE record last updated430 days (about 1 year) later
12 Nov 2026Analysed by vulneraibility.com304 days (about 10 months) later

CVSS vector

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

Metric	Value	What it means
Attack vector	NetworkReachable over the internet or any routable network.	Reachable over the internet or any routable network.
Attack complexity	HighNeeds specific conditions, a race or a particular configuration.	Needs specific conditions, a race or a particular configuration.
Privileges required	NoneThe attacker needs no prior access.	The attacker needs no prior access.
User interaction	NoneNo victim action needed.	No victim action needed.
Scope	UnchangedImpact stays within the vulnerable component.	Impact stays within the vulnerable component.
Confidentiality	NoneNo data disclosure.	No data disclosure.
Integrity	NoneNo unauthorised modification.	No unauthorised modification.
Availability	HighFull outage possible.	Full outage possible.

Common questions

Is CVE-2009-2055 being exploited?

Yes. CVE-2009-2055 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.

How severe is CVE-2009-2055?

CVE-2009-2055 is rated Medium with a CVSS score of 5.9. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2009-2055?

Yes. A fix has been recorded for CVE-2009-2055. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2009-2055 affect?

CVE-2009-2055 affects cisco:ios_xr. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

4 references in the CVE record, grouped by the tags the record gives them.

Advisories (1)

cisco.com /en/US/products/products_security_advisory09186a0080af150f.shtml

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
CISA KEV catalog: exploitation, date added, due date
CISA Vulnrichment (ADP): SSVC decision points
FIRST EPSS: exploit probability and percentile

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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