CVE-2018-15388: Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software WebVPN Denial of Service Vulnerability

Severity: high (CVSS 8.6 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2019-05-03 · updated 2026-08-11
Weakness: CWE-400

Description

A vulnerability in the WebVPN login process of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause increased CPU utilization on an affected device. The vulnerability is due to excessive processing load for existing WebVPN login operations. An attacker could exploit this vulnerability by sending multiple WebVPN login requests to the device. A successful exploit could allow the attacker to increase CPU load on the device, resulting in a denial of service (DoS) condition.

Affected products

Cisco ASA Software: before 9.4.4.34; from 9.5 before 9.6.4.25; from 9.7 before 9.8.4; from 9.9 before 9.9.2.50 — fixed in 9.4.4.34, 9.6.4.25, 9.8.4, 9.9.2.50
Cisco Firepower Threat Defense Software: before 6.2.3.12 — fixed in 6.2.3.12

How to fix

Upgrade to a fixed version: Cisco ASA Software 9.4.4.34, 9.6.4.25, 9.8.4, 9.9.2.50; Cisco Firepower Threat Defense Software 6.2.3.12. Check the vendor advisory for mitigations.

References

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