CVE-2016-6381: Cisco IOS

High severity, CVSS 7.5. EPSS: 3.2% chance of exploitation in the next 30 days.

Cisco IOS 12.4 and 15.0 through 15.6 and IOS XE 3.1 through 3.18 and 16.1 allow remote attackers to cause a denial of service (memory consumption or device reload) via fragmented IKEv1 packets, aka Bug ID CSCuy47382.

Affected products

• Cisco IOS: version 12.4(15)t7 only; version 12.4(15)t8 only; version 12.4(15)t9 only; version 12.4(15)t10 only; version 12.4(15)t11 only; version 12.4(15)t12 only; …
• Cisco IOS XE: version 3.1.0s only; version 3.1.1s only; version 3.1.2s only; version 3.1.3as only; version 3.1.4as only; version 3.1.4s only; …
• Cisco IOS XE 16.1: version 16.1.2 only
• Cisco IOS XE 3.3sg: version 3.3.0sg only; version 3.3.1sg only; version 3.3.2sg only
• Cisco IOS XE 3.3xo: version 3.3.0xo only; version 3.3.1xo only
• Cisco IOS XE 3.4sg: version 3.4.0sg only; version 3.4.1sg only; version 3.4.2sg only; version 3.4.3sg only; version 3.4.4sg only; version 3.4.5sg only; …

Published 2016-10-05. Last modified 2026-06-17.