Vulnerability in Cisco Terminal Service (TS) Agent (CVE-2026-20028)
Summary
Vulnerability in Cisco Terminal Service (TS) Agent (CVE-2026-20028). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
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: Cisco Security Advisories NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-20028 has been found in Cisco Terminal Service (TS) Agent.
Risk of unauthorized operations or information disclosure. CVSS score: 5.0/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Cisco Terminal Service (TS) Agent CVE-2026-20028" on the vendor's site.
CVE-2026-20028 (Cisco Terminal Service (TS) Agent) — CWE-266 / CVSS v3 5.0
Attack vector: remote (network-reachable) / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-266) exists in Cisco Terminal Service (TS) Agent.
Check the vendor advisory for the affected versions of Cisco Terminal Service (TS) Agent.
Severity: Medium (CVSS 5.0/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Cisco Terminal Service (TS) Agent を使っているサービスとバージョンを洗い出す。
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2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- CISCO sec.cloudapps.cisco.com
- web nvd.nist.gov
- web psirt@cisco.com
- web github.com