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High7.5Fortinet

High [CVE-2026-22153] LDAP authentication bypass in Agentless VPN and FSSO

This high-severity Fortinet advisory covers CVE-2026-22153 affecting FortiOS.

FG-IR-25-1052 Published Feb 10, 2026Updated by vendor Jul 4, 2026
Affected products & platforms
FortinetFortiGateFirewallFortiOS
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Summary

CVSSv3 Score:

7.5

An Authentication Bypass by Primary Weakness vulnerability [CWE-305] in FortiOS fnbamd may allow an unauthenticated attacker to bypass LDAP authentication of Agentless VPN or FSSO policy, under specific LDAP server configuration.

Revised on 2026-07-04 00:00:00

Affected versions
  • FortiOS 7.6: 7.6.0 through 7.6.4

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Fixed versions
  • FortiOS 7.6: 7.6.5

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Upgrade per the Affected/Solution table: FortiOS 7.6: 7.6.5.
Temporary workarounds
  • Disable unauthenticated bind on the LDAP server.
  • For example, LDAP unauthenticated binds can be disabled in Windows Active Directory (starting from Windows Server 2019) via the following PowerShell code snippet:
  • $configDN = (Get-ADRootDSE).configurationNamingContext$dirSvcDN = "CN=Directory Service,CN=Windows NT,CN=Services,$configDN"Set-ADObject -Identity $dirSvcDN -Add @{'msDS-Other-Settings'='DenyUnauthenticatedBind=1'}
  • Virtual Patch named "FG-VD-10009566.0day." is available in FMWP db update 26.063

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

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