Overview
Fortinet FortiOS, FortiSwitchMaster, FortiProxy, and FortiWeb contain an improper verification of cryptographic signature vulnerability that may allow an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML message. Please be aware that CVE-2025-59719 pertains to the same problem and is mentioned in the same vendor advisory. Ensure to apply all patches mentioned in the advisory.
https://fortiguard.fortinet.com/psirt/FG-IR-25-647 ; https://docs.fortinet.com/upgrade-tool/fortigate ; https://nvd.nist.gov/vuln/detail/CVE-2025-59718
Key Details
| Property | Value |
|---|---|
| CVE ID | CVE-2025-59718 |
| Vendor / Product | Fortinet — Multiple Products |
| NVD Published | 2025-12-09 |
| NVD Last Modified | 2025-12-17 |
| CVSS 3.1 Score | 9.8 |
| CVSS 3.1 Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Severity | CRITICAL |
| CWE | CWE-347 |
| CISA KEV Added | 2025-12-16 |
| CISA KEV Deadline | 2025-12-23 |
| Known Ransomware Use | No |
CVSS 3.1 Breakdown
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Required Action
CISA BOD 22-01 Deadline: 2025-12-23.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Timeline
| Date | Event |
|---|---|
| 2025-12-16 | Added to CISA Known Exploited Vulnerabilities catalog |
| 2025-12-23 | CISA BOD 22-01 remediation deadline |
References
| Resource | Type |
|---|---|
| NVD — CVE-2025-59718 | Vulnerability Database |
| CISA KEV Catalog Entry | US Government |