Main Vulnerability Database Vulnerabilities #VU148723

Improper certificate validation in FortiOS and FortiProxy - CVE-2026-84393

Published: September 9, 2026

Vulnerability identifier: #VU148723

CSH Severity: High

CVSS v4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-84393

CWE-ID: CWE-295

Exploitation vector: Remote access

Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote non-authenticated attacker to execute arbitrary code.

The vulnerability exists due to improper certificate validation. A remote and unauthenticated attacker can perform a Man-in-the-Middle attack on the communication channel between the ZTNA portal and the backend destination website.

Affected software

FortiOS
FortiProxy

How to mitigate CVE-2026-84393

Install update from vendor's website.

FortiOS - update to 7.6.7
FortiProxy - update to 7.6.7

External References

https://www.fortiguard.com/psirt/FG-IR-26-174

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