What’s Vulnerable › Vulnerabilities

CVE-2020-3133: Cisco Email Security Appliance Content Filter Bypass Vulnerability

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-09-23 · updated 2026-06-17
• Weakness: CWE-20

Description

A vulnerability in the email message scanning of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass configured filters on the device. The vulnerability is due to improper validation of incoming emails. An attacker could exploit this vulnerability by sending a crafted email message to a recipient protected by the ESA. A successful exploit could allow the attacker to bypass the configured content filters, which could allow malicious content to pass through the device.

Affected products

• Cisco Email Security Appliance (ESA): before 13.0 — fixed in 13.0

How to fix

Upgrade to a fixed version: Cisco Email Security Appliance (ESA) 13.0. Check the vendor advisory for mitigations.

References

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-bypass-5Cdv2HMA
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-bypass-5Cdv2HMA

Get alerted when CVE-2020-3133 or the next vulnerability affects your stack