CVE-2020-3132: Cisco Email Security Appliance Shortened URL Denial of Service Vulnerability

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-02-19 · updated 2026-06-17
Weakness: CWE-400

Description

A vulnerability in the email message scanning feature of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to cause a temporary denial of service (DoS) condition on an affected device. The vulnerability is due to inadequate parsing mechanisms for specific email body components. An attacker could exploit this vulnerability by sending a malicious email containing a high number of shortened URLs through an affected device. A successful exploit could allow the attacker to consume processing resources, causing a DoS condition on an affected device. To successfully exploit this vulnerability, certain conditions beyond the control of the attacker must occur.

Affected products

Cisco Cloud Email Security: before 12.5.1-037; before 13.0.0-375 — fixed in 12.5.1-037, 13.0.0-375
Cisco Email Security Appliance (ESA): before 12.5.1-037; before 13.0.0-375 — fixed in 12.5.1-037, 13.0.0-375

How to fix

Upgrade to a fixed version: Cisco Cloud Email Security 12.5.1-037, 13.0.0-375; Cisco Email Security Appliance (ESA) 12.5.1-037, 13.0.0-375. Check the vendor advisory for mitigations.

References

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