Authenticated firewall bypass via connection misattribution
Published Aug 5, 2026 · Updated Aug 5, 2026
Improper privilege assignment in Cisco Terminal Services Agent before 1.4.3 allows remote authenticated users to bypass firewall rules. The Windows network driver incorrectly maps crafted network connections to user accounts, causing attacker traffic to inherit another user's firewall policy. User-level credentials and crafted traffic to the affected host are required; successful exploitation changes policy enforcement without reported data disclosure or service interruption.
Summary
What happened
Improper privilege assignment in Cisco Terminal Services Agent before 1.4.3 allows remote authenticated users to bypass firewall rules. The Windows network driver incorrectly maps crafted network connections to user accounts, causing attacker traffic to inherit another user's firewall policy. User-level credentials and crafted traffic to the affected host are required; successful exploitation changes policy enforcement without reported data disclosure or service interruption.
The record
- CVE
- CVE-2026-20028
- Published
- Aug 5, 2026
- Updated
- Aug 5, 2026
- Vendor
- ClamAV
- Product
- Cisco Terminal Services Agent
- Classifications
- CWE-266, T1562.004
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 5, 2026CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=TSAgent-1.0
- Affected versionversion=TSAgent-1.1
- Affected versionversion=TSAgent-1.2
- Affected versionversion=TSAgent-1.3
- Affected versionversion=TSAgent-1.4
- Affected versionversion=TSAgent-1.4.1
- Affected versionversion=TSAgent-1.4.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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