Unauthenticated traffic interception via hostname mismatch acceptance
Published Sep 8, 2026 · Updated Sep 10, 2026
Certificate validation failure in affected Fortinet FortiOS and FortiProxy releases allows remote attackers to intercept Agentless ZTNA traffic. The Agentless ZTNA portal accepts a backend destination website certificate when its hostname does not match, enabling interception of the portal-to-backend channel. An unauthenticated attacker must attain a man-in-the-middle position on that channel; affected releases are FortiOS 7.6.1 through 7.6.6 and FortiProxy 7.6.2 through 7.6.6, and intercepted traffic can expose or alter data and interrupt service.
Summary
What happened
Certificate validation failure in affected Fortinet FortiOS and FortiProxy releases allows remote attackers to intercept Agentless ZTNA traffic. The Agentless ZTNA portal accepts a backend destination website certificate when its hostname does not match, enabling interception of the portal-to-backend channel. An unauthenticated attacker must attain a man-in-the-middle position on that channel; affected releases are FortiOS 7.6.1 through 7.6.6 and FortiProxy 7.6.2 through 7.6.6, and intercepted traffic can expose or alter data and interrupt service.
The record
- CVE
- CVE-2026-84393
- Published
- Sep 8, 2026
- Updated
- Sep 10, 2026
- Vendor
- Fortinet
- Product
- FortiOS
- Classifications
- CWE-297, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 8, 2026CVE publishedPublication date reported by the CVE source.
- Sep 10, 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=7.6.1 <=7.6.6
What conditions does exploitation require?
What is affected?
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.
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Technologies
Your stack
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Your stack
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