CVE-2021-1403: Cisco IOS XE

High severity, CVSS 7.4. EPSS: 0.6% chance of exploitation in the next 30 days.

A vulnerability in the web UI feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to conduct a cross-site WebSocket hijacking (CSWSH) attack and cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient HTTP protections in the web UI on an affected device. An attacker could exploit this vulnerability by persuading an authenticated user of the web UI to follow a crafted link. A successful exploit could allow the attacker to corrupt memory on the affected device, forcing it to reload and causing a DoS condition.

Affected products

• Cisco IOS XE: version 3.15.1xbs only; version 3.15.2xbs only; version 16.3.1 only; version 16.3.1a only; version 16.3.2 only; version 16.3.3 only; …

Published 2021-03-24. Last modified 2026-06-17.