CVE-2024-20309: Cisco IOS XE

Medium severity, CVSS 5.5. EPSS: 0.1% chance of exploitation in the next 30 days.

A vulnerability in auxiliary asynchronous port (AUX) functions of Cisco IOS XE Software could allow an authenticated, local attacker to cause an affected device to reload or stop responding. This vulnerability is due to the incorrect handling of specific ingress traffic when flow control hardware is enabled on the AUX port. An attacker could exploit this vulnerability by reverse telnetting to the AUX port and sending specific data after connecting. A successful exploit could allow the attacker to cause the device to reset or stop responding, resulting in a denial of service (DoS) condition.

Affected products

• Cisco IOS XE: version 3.2.0se only; version 3.2.1se only; version 3.2.2se only; version 3.2.3se only; version 3.3.0se only; version 3.3.0sq only; …

Published 2024-03-27. Last modified 2026-06-17.