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Cisco Releases Patch for Serious VPN Hijacking Bug in Secure Client

Cisco recently announced patches for two high severity vulnerabilities in Secure Client, their enterprise VPN application, as well as fixes for several other security flaws in various products:

The first vulnerability, identified as CVE-2024-20337, affects the Linux, macOS and Windows versions of Secure Client and could be exploited remotely, without authentication, in carriage return line character injection (CRLF) attacks.

Because the input provided by the user is not sufficiently validated, an attacker who could trick a user into clicking on a forged link when establishing a VPN session could execute arbitrary scripts in the victim's browser or access sensitive information, such as SAML tokens.

"The attacker could then use the token to establish a remote access VPN session with the privileges of the affected user. The individual hosts and services behind the VPN termination would still require additional credentials for successful access," Cisco explains in its advisory.

According to Cisco, only Secure Client instances where the VPN termination is configured with the SAML External Browser function are vulnerable.

The technology giant has corrected the flaw with the release of Secure Client versions 4.10.08025 and Iterations prior to version 4.10.04065 are not vulnerable, and no patch is available for version 5.0.

The second high severity bug, followed by CVE-2024-20338, only concerns Secure Client for Linux and requires authentication for successful exploitation. Version of the VPN application resolves the bug.

"An attacker could exploit this vulnerability by copying a malicious library file to a specific directory on the file system and persuading an administrator to restart a specific process. Successful exploitation could allow the attacker to execute arbitrary code on an affected device with root privileges", explains Cisco.

In addition, Cisco has announced patches for several medium severity vulnerabilities in other products, such as AppDynamics Controller and Duo Authentication for Windows Logon and RDP. These vulnerabilities could potentially lead to data leakage and bypass secondary authentication. However, some medium severity flaws in the Small Business 100, 300 and 500 APs remain unpatched due to their end-of-life status.

Cisco stresses that it is not aware of any active exploitation of these vulnerabilities in the wild. Further details and updates are available on Cisco's Security Advisories page, so that administrators can take the necessary steps to secure their systems.


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