Risk Letters

Exploited vulnerability

CVE-2025-59718

TLP:CLEAR

Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability

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.

Facts

  • Vendor: Fortinet
  • Product: Multiple Products
  • CVSS: 9.1
  • EPSS (probability of exploitation within 30 days): 68.3 %
  • On CISA's Known Exploited Vulnerabilities list since: 16 December 2025
  • First known exploitation: 16 December 2025
  • CISA's deadline for US federal agencies: 23 December 2025
  • Weakness: CWE-347
  • First seen by Risk Letters: 16 December 2025

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Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD