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Fortinet Releases Security Advisory for FortiCloud SSO Login Authentication Bypass

The security advisory address two vulnerabilities that could allow an attacker to bypass the FortiCloud SSO login authentication via a crafted SAML message

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Summary

The security advisory address two vulnerabilities that could allow an attacker to bypass the FortiCloud SSO login authentication via a crafted SAML message


Threat details

Potential exploitation of CVE-2025-59718 and CVE-2025-59719

Researchers have reported evidence of malicious SSO logins on FortiGate devices following disclosure of CVE-2025-59718 and CVE-2025-59719.


Introduction

Fortinet has released a security advisory to address two critical vulnerabilities affecting FortiOS, FortiWeb, FortiProxy and FortiSwitchManager. Devices are only vulnerable if the FortiCloud SSO login feature is enabled when registering the device to FortiCare.

  • CVE-2025-59718 - an 'improper verification of cryptographic signature' vulnerability with - CVSSv3 score: 9.1.

  • CVE-2025-59719 - an 'improper verification of cryptographic signature' vulnerability with - CVSSv3 score: 9.1.


Threat updates

Date Update
16 Dec 2025 Added details regarding potential exploitation of CVE-2025-59718 and CVE-2025-59719

Remediation advice

Affected organisations are encouraged to review the Fortinet PSIRT FG-IR-25-647 and apply the relevant updates as soon as possible.


Definitive source of threat updates


Last edited: 16 December 2025 12:14 pm