CVE-2020-3204: Cisco IOS

Medium severity, CVSS 6.7. EPSS: 0.4% chance of exploitation in the next 30 days.

A vulnerability in the Tool Command Language (Tcl) interpreter of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, local attacker with privileged EXEC credentials to execute arbitrary code on the underlying operating system (OS) with root privileges. The vulnerability is due to insufficient input validation of data passed to the Tcl interpreter. An attacker could exploit this vulnerability by loading malicious Tcl code on an affected device. A successful exploit could allow the attacker to cause memory corruption or execute the code with root privileges on the underlying OS of the affected device.

Affected products

• Cisco IOS: version 12.2(6)i1 only; version 12.2(33)sre only; version 12.2(33)sre0a only; version 12.2(33)sre1 only; version 12.2(33)sre2 only; version 12.2(33)sre3 only; …
• Cisco IOS XE: version 3.2.0se only; version 3.2.0sg only; version 3.2.1se only; version 3.2.1sg only; version 3.2.2se only; version 3.2.2sg only; …

Published 2020-06-03. Last modified 2026-06-17.