#VU47108 Improper validation of certificate with host mismatch in Fortinet FortiClient for Windows

Vulnerability identifier: #VU47108

Vulnerability risk: High

CVSSv4.0: 8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: N/A

CWE-ID: CWE-297

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Fortinet FortiClient for Windows
Server applications / Other server solutions

Vendor: Fortinet, Inc

Description

The vulnerability allows a remote attacker to perform a MitM attack.

The vulnerability exists in FortiClient SSL-VPN client due to the application does not properly validate server certificates and checks only if the certificate was issued by a trusted CA or Fortinet itself. A remote attacker can supply a certificate, issued to a different Fortigate router and perform a Man-in-the-Middle attack.

Successful exploitation of the vulnerability may allow an attacker to intercept and descrypt all traffic, protected with Fortinet SSL-VPN.

Mitigation
Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

Fortinet FortiClient for Windows: 0, 1.0.0 - 1.0.5, 1.2.0 - 1.2.5, 4.0.0 - 4.0.2, 4.1.0, 4.2.0, 4.3.0 - 4.3.3.445, 5.0.1 - 5.0.11, 5.2.0 - 5.2.028, 5.4.0 - 5.4.5, 5.6.0 - 5.6.6, 6.0.0 - 6.0.8, 6.2.0 - 6.2.2, 6.4.0

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External links
https://securingsam.com/breaching-the-fort/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.