CVE-2019-12706: Cisco Email Security Appliance Firmware

High severity, CVSS 7.5. EPSS: 1.3% chance of exploitation in the next 30 days.

A vulnerability in the Sender Policy Framework (SPF) functionality of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass the configured user filters on an affected device. The vulnerability exists because the affected software insufficiently validates certain incoming SPF messages. An attacker could exploit this vulnerability by sending a custom SPF packet to an affected device. A successful exploit could allow the attacker to bypass the configured header filters, which could allow malicious content to pass through the device.

Affected products

• Cisco Email Security Appliance Firmware: before 13.5.0 (fixed in 13.5.0)

Published 2019-10-02. Last modified 2026-06-17.