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CVE-2026-20028— Cisco Terminal Services Agent Firewall Rules Bypass Vulnerability

Quick assessment

Affected
Cisco Cisco Terminal Services Agent
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Cisco Terminal Services Agent是美国Cisco公司的一款终端服务代理软件。 Cisco Terminal Services Agent TSAgent-1.3版本、TSAgent-1.4.2版本、TSAgent-1.2版本、TSAgent-1.4版本、TSAgent-1.0版本、TSAgent-1.4.1版本和TSAgent-1.1版本存在权限许可和访问控制问题漏洞，该漏洞源于网络连接与用户账户映射不正确，可能导致经过身份验证的远程攻击者利用用户级凭据发送特制网络流量，绕过防火

CVSS 5.0 · Medium EPSS 0.35% · P26

Possible ATT&CK Techniques 1 AI

T1548.002 · Bypass User Account Control

Affected Version Matrix 7

VendorProduct Version RangeStatus
Cisco Cisco Terminal Services Agent TSAgent-1.3 affected
TSAgent-1.4.2 affected
TSAgent-1.2 affected
TSAgent-1.4 affected
TSAgent-1.0 affected
TSAgent-1.4.1 affected
TSAgent-1.1 affected
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I. Basic Information for CVE-2026-20028

Vulnerability Information
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Vulnerability Title
Cisco Terminal Services Agent Firewall Rules Bypass Vulnerability
Source: CVE Program / CVE List V5
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
特权授予不正确
Source: CVE Program / CVE List V5
Vulnerability Title
Cisco Terminal Services Agent 权限许可和访问控制问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Cisco Terminal Services Agent是美国Cisco公司的一款终端服务代理软件。 Cisco Terminal Services Agent TSAgent-1.3版本、TSAgent-1.4.2版本、TSAgent-1.2版本、TSAgent-1.4版本、TSAgent-1.0版本、TSAgent-1.4.1版本和TSAgent-1.1版本存在权限许可和访问控制问题漏洞，该漏洞源于网络连接与用户账户映射不正确，可能导致经过身份验证的远程攻击者利用用户级凭据发送特制网络流量，绕过防火
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Cisco Cisco Terminal Services Agent TSAgent-1.3 -

II. Public POCs for CVE-2026-20028

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III. Intelligence Information for CVE-2026-20028

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Vendor Advisories for CVE-2026-20028 (1)

Same Patch Batch · Cisco · 2026-08-05 · 23 CVEs total

CVE-2026-20304 9.9 CRITICAL Cisco Catalyst SD-WAN Security Hardening Release - Access Control Vulnerabilities
CVE-2026-20303 9.9 CRITICAL Cisco Catalyst SD-WAN Security Hardening Release - Input Validation Vulnerabilities
CVE-2026-20272 9.8 CRITICAL Cisco IOS XE Software Security Hardening Release
CVE-2026-20310 9.1 CRITICAL Cisco SD-WAN Software Security Hardening Release - Improper Link Resolution Before File Ac
CVE-2026-20267 9.0 CRITICAL Cisco IOS XE Software Security Hardening Release
CVE-2026-20312 8.8 HIGH Cisco Catalyst SD-WAN Security Hardening Release - Information Disclosure Vulnerabilities
CVE-2026-20200 8.8 HIGH Cisco Integrated Management Controller Argument Injection and Remote Code Execution Vulner
CVE-2026-20263 8.6 HIGH Cisco IOS XE Software Blocks Extensible Exchange Protocol Denial of Service Vulnerability
CVE-2026-20268 8.6 HIGH Cisco IOS XE Software Security Hardening Release
CVE-2026-20269 8.6 HIGH Cisco IOS XE Software Security Hardening Release
CVE-2026-20270 8.6 HIGH Cisco IOS XE Software Security Hardening Release
CVE-2026-20271 8.6 HIGH Cisco IOS XE Software Security Hardening Release
CVE-2026-20273 8.6 HIGH Cisco IOS XE Software Security Hardening Release
CVE-2026-20301 8.6 HIGH Cisco IOS Software and IOS XE Software Extensible Messaging Client Protocol Denial of Serv
CVE-2026-20313 7.7 HIGH Cisco Catalyst SD-WAN Security Hardening Release - Memory Corruption Vulnerabilities
CVE-2026-20124 7.7 HIGH Cisco IOS XE Software SNMP Denial of Service Vulnerability
CVE-2026-20294 6.5 MEDIUM Cisco Catalyst SD-WAN Manager Information Disclosure Vulnerability
CVE-2026-20288 6.5 MEDIUM Cisco IMC Remote Code Execution Vulnerability Remote Code Execution Vulnerability
CVE-2026-20311 6.3 MEDIUM Cisco IOS XE Software Web UI Denial of Service Vulnerability
CVE-2026-20289 5.7 MEDIUM Cisco RoomOS Logging Subsystem Information Disclosure Vulnerability

Showing top 20 of 23 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same vendor: Cisco
Same weakness: CWE-266

V. Comments for CVE-2026-20028

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