CVE-2021-1378: Cisco Staros

High severity, CVSS 7.5. EPSS: 1.5% chance of exploitation in the next 30 days.

A vulnerability in the SSH service of the Cisco StarOS operating system could allow an unauthenticated, remote attacker to cause an affected device to stop processing traffic, resulting in a denial of service (DoS) condition. The vulnerability is due to a logic error that may occur under specific traffic conditions. An attacker could exploit this vulnerability by sending a series of crafted packets to an affected device. A successful exploit could allow the attacker to prevent the targeted service from receiving any traffic, which would lead to a DoS condition on the affected device.

Affected products

• Cisco Staros: from 21.9.0, up to and including 21.19.10

Published 2021-02-17. Last modified 2026-06-17.