CVE-2026-20028
Cisco Terminal Services Agent Firewall Rules Bypass Vulnerability
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.
INFO
Published Date :
Aug. 5, 2026, 5:16 p.m.
Last Modified :
Aug. 5, 2026, 6:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-20028
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Cisco Terminal Service Agent software.
- Apply vendor-provided security patches.
- Review and re-apply firewall rules.
- Monitor network traffic for suspicious activity.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-20028.
| URL | Resource |
|---|---|
| https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ts-agent-fw-bypass-MYBTMrev |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-20028 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-20028
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-20028 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-20028 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 05, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-20028', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-05T17:19:39.672252Z'} -
New CVE Received by [email protected]
Aug. 05, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Cisco', 'product': 'Cisco Terminal Services Agent', 'versions': [{'status': 'affected', 'version': 'TSAgent-1.3'}, {'status': 'affected', 'version': 'TSAgent-1.4.2'}, {'status': 'affected', 'version': 'TSAgent-1.2'}, {'status': 'affected', 'version': 'TSAgent-1.4'}, {'status': 'affected', 'version': 'TSAgent-1.0'}, {'status': 'affected', 'version': 'TSAgent-1.4.1'}, {'status': 'affected', 'version': 'TSAgent-1.1'}], 'defaultStatus': 'unknown'}] Added 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. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N Added CWE CWE-266 Added Reference https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ts-agent-fw-bypass-MYBTMrev