#VU54205 UNIX symbolic link following in Fortinet FortiClient for Windows - CVE-2021-26089

Vulnerability identifier: #VU54205

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-26089

CWE-ID: CWE-61

Exploitation vector: Local

Exploit availability: No

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

Vendor: Fortinet, Inc

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a symlink following issue in FortiClient installer for MacO. A local user can create a specially crafted symbolic link to a critical file on the system and overwrite it with privileges of the application.

Successful exploitation of this vulnerability may result in privilege escalation.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Fortinet FortiClient for Windows: 6.0.0 - 6.0.10, 6.2.0 - 6.2.8, 6.4.0 - 6.4.3

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External links
https://www.zerodayinitiative.com/advisories/ZDI-21-693/
https://www.fortiguard.com/psirt/FG-IR-21-022

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

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