CVE-2024-20307: Cisco IOS

High severity, CVSS 7.5. EPSS: 0.7% 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 overflow, 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 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 15.1(2)sg8 only; version 15.1(2)sy8 only; version 15.1(2)sy9 only; version 15.1(2)sy10 only; version 15.1(2)sy11 only; version 15.1(2)sy12 only; …
• Cisco IOS XE: version 3.4.8sg only; version 3.7.4e only; version 3.7.5e only; version 3.8.2e only; version 3.8.3e only; version 3.8.4e only; …

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