CVE-2019-15988: Cisco Email Security Appliance Firmware

Medium severity, CVSS 5.3. EPSS: 1% chance of exploitation in the next 30 days.

A vulnerability in the antispam protection mechanisms of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass the URL reputation filters on an affected device. The vulnerability is due to insufficient input validation of URLs. An attacker could exploit this vulnerability by crafting the URL in a particular way. A successful exploit could allow the attacker to bypass the URL reputation filters that are configured for the affected device, which could allow malicious URLs to pass through the device.

Affected products

• Cisco Email Security Appliance Firmware: up to and including 12.5.0

Published 2019-11-26. Last modified 2026-06-17.