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CVE-2011-1640

Cisco IOS - Ethernet-LLDP Component

Cisco CVSS 7.5 Updated April 30, 2026

Executive Risk Summary

"A denial of service vulnerability exists in the ethernet-lldp component of Cisco IOS due to improper handling of a large number of LLDP Management Address (MA) TLVs. This allows remote attackers to cause a device crash via crafted LLDPDUs."

Anticipated Attack Path

  1. 1. Attacker sends crafted LLDPDUs to the vulnerable device
  2. 2. Device fails to properly handle the LLDPDUs, leading to a crash
  3. 3. Network availability is impacted due to the device crash

Am I Vulnerable?

  • Verify Cisco IOS version is prior to 12.2(33)SXJ1
  • Check for LLDP protocol support on the device
  • Monitor network logs for suspicious LLDP traffic

Operational Audit Arsenal

Target Type Network Device
Target Asset ethernet-lldp
Standard Path Cisco IOS

Manual Verification Required

This is a non-Windows asset (Cisco). Use the target asset details and official path provided above to verify your current version against the official vendor advisories listed below.

Patch Impact Forecast

Reboot Required Likely

Network downtime during reboot

Internal Work Notes

Cisco IOS device crash due to LLDP vulnerability, requiring patch update to 12.2(33)SXJ1 or later

Technical Intelligence & Operational Utilities • Delivered Weekly

Intelligence Sources

Related Cisco Threats

Data compiled from NVD, MSRC, and CISA KEV Catalog. Intelligence synthesized via AI. Scripts provided for diagnostic purposes under MIT License.