Cisco Terminal Services Agent up to TSAgent-1.4.2 Network Driver privileges management

Summaryinfo

A vulnerability classified as very critical was found in Cisco Terminal Services Agent up to TSAgent-1.4.2. This issue affects some unknown processing of the component Network Driver. Executing a manipulation can lead to privileges management. This vulnerability is tracked as CVE-2026-20028. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability has been found in Cisco Terminal Services Agent up to TSAgent-1.4.2 and classified as very critical. This vulnerability affects an unknown function of the component Network Driver. The manipulation with an unknown input leads to a privileges management vulnerability. The CWE definition for the vulnerability is CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

A vulnerability in the network driver of Cisco Terminal Service (TS) Agent could allow an authenticated, remote attacker to bypass firewall rules that are associated with the account of the attacker. This vulnerability is due to an incorrect mapping of network connections to user accounts. An attacker with at least user-level credentials could exploit this vulnerability by sending crafted network traffic to an affected device. A successful exploit could allow the attacker to inherit the firewall rules associated with a different user in the system.

The advisory is available at sec.cloudapps.cisco.com. This vulnerability was named CVE-2026-20028 since 10/08/2025. The exploitation appears to be easy. The attack can be initiated remotely. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 08/05/2026). This vulnerability is assigned to T1068 by the MITRE ATT&CK project.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• Cisco

Name

• Terminal Services Agent

Version

• TSAgent-1.0
• TSAgent-1.1
• TSAgent-1.2
• TSAgent-1.3
• TSAgent-1.4
• TSAgent-1.4.1
• TSAgent-1.4.2

License

• commercial

Website

• Vendor: https://www.cisco.com/

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