Fortinet FortiOS SSL VPN Improper Authentication Vulnerability
- Severity
- Critical9.8CVSS 3.1, Critical
- EPSS
- 49%
- Published
- 24 Jul 2020
- Updated
- 12 Aug 2026
Description
Title, description and vendor guidance are quoted from the source records.
An improper authentication vulnerability in SSL VPN in FortiOS 6.4.0, 6.2.0 to 6.2.3, 6.0.9 and below may result in a user being able to log in successfully without being prompted for the second factor of authentication (FortiToken) if they changed the case of their username.
Weakness: CWE-178, CWE-287
Known exploited
Added to CISA KEV on 3 Nov 2021
Federal remediation due date: 3 May 2022
Known use in ransomware campaigns
Required action: Apply updates per vendor instructions.
Exploit prediction
49% probability of exploitation in the next 30 days (percentile 99%).
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected products
Patcharo shows this vulnerability for information but does not match versions for this product yet.
- n/a Fortinet FortiOS · FortiOS 6.4.0, 6.2.0 to 6.2.3, 6.0.9 and below
References
Provenance
Every fact on this page comes from the sources below. Nothing is written by an AI.
- Fortinet (CVE record)
- Fortinet (CVE record) · 27 Sept 2026, 23:46 UTC · Parser patcharo-cve5/1.1.0
- CISA Known Exploited Vulnerabilities
- CISA Known Exploited Vulnerabilities · 27 Sept 2026, 23:42 UTC · Parser patcharo-kev/1.0.0
- NVD
- NVD · 27 Sept 2026, 23:44 UTC · Parser patcharo-nvd/1.0.0
- FIRST EPSS
- FIRST EPSS · 27 Sept 2026, 23:46 UTC · Parser patcharo-epss/1.0.0
Last verified: 28 Sept 2026, 02:31 UTC