CVE-2026-20028
Cisco Terminal Services Agent Firewall Rules Bypass Vulnerability
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Cisco Terminal Services Agent Firewall Rules Bypass Vulnerability
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.
- Record
CVE-2026-20028- CVSS 3.1
- 5.0 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N - Weakness
- CWE-266
- Updated
- 2026-11-02
EUVDEUVD-2026-53447
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.
- Record
EUVD-2026-53447- CVSS 3.1
- 5.0 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-6vj9-8q5m-xjpv
A vulnerability in the network driver of Cisco Terminal Service (TS) Agent could allow an...
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.
- Record
GHSA-6vj9-8q5m-xjpv- CVSS 3.1
- 5.0 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N - Weakness
- CWE-266
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-20028- CVSS 3.1
- 5.0 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N - Weakness
- CWE-266
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-20028 is a medium vulnerability (CVSS 5.0) in Cisco Terminal Services Agent, published August 5, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.35%, the 28th percentile. No source names a fixed version.