FortiAuthenticator 6.3-6.6.x: Auth Bypass via Unprotected File Upload
CVE-2026-21743 Published on February 10, 2026
A missing authorization vulnerability in Fortinet FortiAuthenticator 6.6.0 through 6.6.6, FortiAuthenticator 6.5 all versions, FortiAuthenticator 6.4 all versions, FortiAuthenticator 6.3 all versions may allow a read-only user to make modification to local users via a file upload to an unprotected endpoint.
Vulnerability Analysis
CVE-2026-21743 can be exploited with network access, and requires user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
What is an AuthZ Vulnerability?
The software does not perform an authorization check when an actor attempts to access a resource or perform an action.
CVE-2026-21743 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-21743
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Affected Versions
Fortinet FortiAuthenticator:- Version 6.6.0, <= 6.6.6 is affected.
- Version 6.5.0, <= 6.5.7 is affected.
- Version 6.4.0, <= 6.4.11 is affected.
- Version 6.3.0, <= 6.3.5 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.