Fortinet FortiOS 7.0-7.6 SAML Auth Bypass via Signature Verify Flaw
CVE-2025-59718 Published on December 9, 2025
A improper verification of cryptographic signature vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2.0 through 7.2.11, FortiOS 7.0.0 through 7.0.17, FortiProxy 7.6.0 through 7.6.3, FortiProxy 7.4.0 through 7.4.10, FortiProxy 7.2.0 through 7.2.14, FortiProxy 7.0.0 through 7.0.21, FortiSwitchManager 7.2.0 through 7.2.6, FortiSwitchManager 7.0.0 through 7.0.5 allows an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML response message.
Known Exploited Vulnerability
This Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. 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.
The following remediation steps are recommended / required by December 23, 2025: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Vulnerability Analysis
CVE-2025-59718 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. This vulnerability is known to be actively exploited by threat actors in an automatable fashion. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.
Weakness Type
Improper Verification of Cryptographic Signature
The software does not verify, or incorrectly verifies, the cryptographic signature for data.
Products Associated with CVE-2025-59718
You can be notified by email with stack.watch whenever vulnerabilities like CVE-2025-59718 are published in these products:
Affected Versions
Fortinet FortiOS:- Version 7.6.0, <= 7.6.3 is affected.
- Version 7.4.0, <= 7.4.8 is affected.
- Version 7.2.0, <= 7.2.11 is affected.
- Version 7.0.0, <= 7.0.17 is affected.
- Version 7.6.0, <= 7.6.3 is affected.
- Version 7.4.0, <= 7.4.10 is affected.
- Version 7.2.0, <= 7.2.14 is affected.
- Version 7.0.0, <= 7.0.21 is affected.
- Version 7.2.0, <= 7.2.6 is affected.
- Version 7.0.0, <= 7.0.5 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.