Vulnerability identifier: #VU54787

Vulnerability risk: High

CVSSv3.1: 7.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-24020

CWE-ID: CWE-325

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Fortinet FortiMail
Server applications / IDS/IPS systems, Firewalls and proxy servers

Vendor: Fortinet, Inc

Description

The vulnerability allows a remote attacker to bypass signature verification.

The vulnerability exists due to a missing cryptographic step in the implementation of the hash digest algorithm in FortiMail. A remote non-authenticated attacker can tamper with signed URLs by appending further data which allows bypass of signature verification.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Fortinet FortiMail: 6.2.0 - 6.4.4

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External links
http://fortiguard.com/advisory/FG-IR-21-027

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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.