CVE-2026-20028 Cisco Terminal Services Agent Firewall Rules Bypass Vulnerability
An authenticated attacker can bypass firewall rules by exploiting incorrect network connection mapping in Cisco Terminal Services Agent.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-20028?
CVE-2026-20028 is a medium-severity vulnerability in Cisco Terminal Services Agent, published on 5 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-266
Which versions are affected by CVE-2026-20028?
How do I fix CVE-2026-20028?
No fix has been published for CVE-2026-20028 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-20028 being exploited?
There is no known exploitation of CVE-2026-20028 in the wild and no public exploit code.
Sources
Also known as GHSA-6vj9-8q5m-xjpv.