What’s Vulnerable › Vulnerabilities

CVE-2019-15971: Cisco Email Security Appliance MP3 Content Filter Bypass Vulnerability

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-11-26 · updated 2026-06-17
• Weakness: CWE-20

Description

A vulnerability in the MP3 detection engine of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass configured content filters on the device. The vulnerability is due to improper validation of certain MP3 file types. An attacker could exploit this vulnerability by sending a crafted MP3 file through the targeted device. A successful exploit could allow the attacker to bypass configured content filters that would normally drop the email.

Affected products

• Cisco Email Security Appliance: before 13.0 — fixed in 13.0

How to fix

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

References

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20191120-esa-mp3-bypass
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20191120-esa-mp3-bypass

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