CVE-2025-59718
Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 23 December 2025). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 68.29% probability · 99th percentile
- CISA KEV
- Listed 16 December 2025 · due 23 December 2025
- Weakness
- CWE-347
- Affected
- fortinet/fortiproxy · fortinet/fortiswitchmanager · fortinet/fortios · siemens/ruggedcom ape1808 firmware
- Source
- psirt@fortinet.com
CISA notes
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. 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
References
- https://fortiguard.fortinet.com/psirt/FG-IR-25-647Vendor Advisory
- https://arcticwolf.com/resources/blog/arctic-wolf-observes-malicious-sso-logins-following-disclosure-cve-2025-59718-cve-2025-59719/Third Party Advisory
- https://cert-portal.siemens.com/productcert/html/ssa-864900.htmlThird Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-59718US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.