CVE-2018-15460: Cisco Email Security Appliance URL Filtering Denial of Service Vulnerability

Severity: high (CVSS 8.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2019-01-10 · updated 2026-06-17
Weakness: CWE-20

Description

A vulnerability in the email message filtering feature of Cisco AsyncOS Software for Cisco Email Security Appliances (ESA) could allow an unauthenticated, remote attacker to cause the CPU utilization to increase to 100 percent, causing a denial of service (DoS) condition on an affected device. The vulnerability is due to improper filtering of email messages that contain references to whitelisted URLs. An attacker could exploit this vulnerability by sending a malicious email message that contains a large number of whitelisted URLs. A successful exploit could allow the attacker to cause a sustained DoS condition that could force the affected device to stop scanning and forwarding email messages.

Affected products

Cisco Asyncos: before 11.0.2-044_md; from 11.1.0 before 11.1.2-023_md — fixed in 11.0.2-044_md, 11.1.2-023_md

How to fix

Upgrade to a fixed version: Cisco Asyncos 11.0.2-044_md, 11.1.2-023_md. Check the vendor advisory for mitigations.

References

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