CVE-2024-20308: Cisco IOS

High severity, CVSS 7.5. EPSS: 0.8% chance of exploitation in the next 30 days.

A vulnerability in the IKEv1 fragmentation code of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a heap underflow, resulting in an affected device reloading. This vulnerability exists because crafted, fragmented IKEv1 packets are not properly reassembled. An attacker could exploit this vulnerability by sending crafted UDP packets to an affected system. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. Note: Only traffic that is directed to the affected system can be used to exploit this vulnerability. This vulnerability can be triggered by IPv4 and IPv6 traffic..

Affected products

• Cisco IOS: version 12.4(22)md only; version 12.4(22)md1 only; version 12.4(22)md2 only; version 12.4(22)mda only; version 12.4(22)mda1 only; version 12.4(22)mda2 only; …
• Cisco IOS XE: version 3.3.0sg only; version 3.3.1sg only; version 3.3.2sg only; version 3.4.0sg only; version 3.4.1sg only; version 3.4.2sg only; …

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