CVE-2016-6393: Cisco IOS

High severity, CVSS 7.5. EPSS: 4.6% chance of exploitation in the next 30 days.

The AAA service in Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 2.1 through 3.18 and 16.2 allows remote attackers to cause a denial of service (device reload) via a failed SSH connection attempt that is mishandled during generation of an error-log message, aka Bug ID CSCuy87667.

Affected products

• Cisco IOS: from 12.0, up to and including 12.4; from 15.0, up to and including 15.6
• Cisco IOS XE: from 2.1.0, up to and including 3.18.0; version 16.2 only

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