Vulnerability identifier: #VU84879

Vulnerability risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-42756

CWE-ID: CWE-121

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Fortinet FortiWeb
Server applications / Remote management servers, RDP, SSH

Vendor: Fortinet, Inc

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in the proxy daemon. A remote unauthenticated attacker can send a specially crafted HTTP request to the system, trigger a stack-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Fortinet FortiWeb: 6.4.0 - 6.4.2, 6.3.0 - 6.3.16, 6.2.0 - 6.2.6, 5.7.0 - 5.7.3, 5.8.0 - 5.8.7, 6.0.0 - 6.0.7, 6.1.0 - 6.1.2, 5.9.0 - 5.9.1, 5.6.0 - 5.6.2

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External links
http://www.fortiguard.com/psirt/FG-IR-21-186

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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.