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CVE-2026-20004

Cisco IOS XE Software - TLS Library

Cisco CVSS 7.4 Updated March 31, 2026

Executive Risk Summary

"A vulnerability in the TLS library of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to exhaust the available memory of an affected device, resulting in a denial of service (DoS) condition. This vulnerability is due to improper management of memory resources during TLS connection setup."

Anticipated Attack Path

  1. 1. An attacker triggers the conditions that cause memory increase by repeatedly attempting EAP authentication or using a man-in-the-middle attack.
  2. 2. The attacker exploits the vulnerability by resetting TLS connections between the affected device and other devices, further exhausting available memory.
  3. 3. The affected device's memory is exhausted, resulting in an unexpected reload and a denial of service (DoS) condition.

Am I Vulnerable?

  • Is your Cisco IOS XE Software version affected by this vulnerability?
  • Are local EAP authentication or other TLS connection setups enabled on your device?
  • Have you applied the necessary patches or workarounds to mitigate this vulnerability?

Operational Audit Arsenal

Target Type Network Device
Target Asset Cisco IOS XE Software
Standard Path Network Infrastructure

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

Potential network disruption during patch application

Internal Work Notes

CVE-2026-20004: Potential DoS vulnerability in Cisco IOS XE Software TLS library, requiring patch application and configuration review.

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