CVE-2021-1237: Cisco AnyConnect Secure Mobility Client for Windows DLL Injection Vulnerability

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-01-13 · updated 2026-06-17
Weakness: CWE-427

Description

A vulnerability in the Network Access Manager and Web Security Agent components of Cisco AnyConnect Secure Mobility Client for Windows could allow an authenticated, local attacker to perform a DLL injection attack. To exploit this vulnerability, the attacker would need to have valid credentials on the Windows system. The vulnerability is due to insufficient validation of resources that are loaded by the application at run time. An attacker could exploit this vulnerability by inserting a configuration file in a specific path in the system which, in turn, causes a malicious DLL file to be loaded when the application starts. A successful exploit could allow the attacker to execute arbitrary code on the affected machine with SYSTEM privileges.

Affected products

Cisco AnyConnect Secure Mobility Client: before 4.9.04043 — fixed in 4.9.04043

How to fix

Upgrade to a fixed version: Cisco AnyConnect Secure Mobility Client 4.9.04043. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2021-1237 or the next vulnerability affects your stack