FSSO DC Agent and Collector authentication bypass in Fortinet FortiOS

1) Improper authentication

EUVDB-ID: #VU54848

Risk: Medium

CVSSv3.1: 5.5 [CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-26088

CWE-ID: CWE-287 - Improper Authentication

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass authentication process.

The vulnerability exists due to an error in FSSO Collector when processing authentication requests. A remote attacker can send specifically crafted UDP login notification packets to bypass any firewall authentication rule and access the protected network.

The vulnerability affects both the FSSO DC Agent and Collector.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

FortiOS: 6.0.0 - 7.0.0

External links

http://fortiguard.com/advisory/FG-IR-20-191

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

Is there known malware, which exploits this vulnerability?

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