Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability (CVE-2025-59718)
Severity: critical · Patch status: unknown · Since 2025-12-16 · CVE-2025-59718
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. CISA added CVE-2025-59718 to its Known Exploited Vulnerabilities catalog on Dec 16, 2025, which means attackers are exploiting it in the wild.
What to do
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- US federal agencies must remediate by Dec 23, 2025 (BOD 22-01); treat that as the outer limit.
Sources
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