Fortinet: ZTNA Portal Improper Certificate Validation

Description

An improper certificate validation vulnerability [CWE-295] in FortiOS and FortiProxy Agentless ZTNA portal may allow a remote and unauthenticated attacker to perform a Man-in-the-Middle attack on the communication channel between the ZTNA portal and the backend destination website. Revised on 2026-09-08 00:00:00

What to do

Install the fixed versions listed in the official advisory. If you cannot update right away, apply the workarounds or mitigations it describes and limit access to the affected service.

Details

Vendor

Fortinet

Product

FortiOS, FortiProxy

Affected versions

FortiOS 7.6: from 7.6.1 to 7.6.6 — fixed in 7.6.7
FortiProxy 7.6: from 7.6.2 to 7.6.6 — fixed in 7.6.7 (from the advisory and NVD; check the exact builds in the official advisory)

CVSS score

8.1

Actively exploited

Not known at this time

Source

Fortinet PSIRT – original advisory

Published

September 8, 2026

The description and the recommended action are quoted from the public advisory (the action is our generic advice); severity, exploitation status and affected versions are compiled automatically from public sources and may contain errors. The vendor's original advisory prevails: check it before taking action. This information is provided without warranty and does not replace a professional assessment.