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Fortinet Fortigate LDAP authentication bypass in Agentless VPN and FSSO (FG-IR-25-1052)

high Nessus Plugin ID 298512

Synopsis

Fortinet Firewall is missing one or more security-related updates.

Description

The version of Fortigate installed on the remote host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the FG-IR-25-1052 advisory.

 - An Authentication Bypass by Primary Weakness vulnerability [CWE-305] vulnerability in Fortinet FortiOS 7.6.0 through 7.6.4 may allow an unauthenticated attacker to bypass LDAP authentication of Agentless VPN or FSSO policy, when the remote LDAP server is configured in a specific way. (CVE-2026-22153)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

For 7.6.x, upgrade to Fortigate version 7.6.5 or later.

See Also

https://www.fortiguard.com/psirt/FG-IR-25-1052

Plugin Details

Severity: High

ID: 298512

File Name: fortigate_FG-IR-25-1052.nasl

Version: 1.1

Type: local

Family: Firewalls

Published: 2/10/2026

Updated: 2/10/2026

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

CVSS v2

Risk Factor: High

Base Score: 7.6

Temporal Score: 5.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-22153

CVSS v3

Risk Factor: High

Base Score: 8.1

Temporal Score: 7.1

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:fortinet:fortios

Required KB Items: Host/Fortigate/model, Host/Fortigate/version, Settings/ParanoidReport

Exploit Ease: No known exploits are available

Patch Publication Date: 2/10/2026

Vulnerability Publication Date: 2/10/2026

Reference Information

CVE: CVE-2026-22153