Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability
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
What happened
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.
CISA lists it as exploited, added 16 Dec 2025.
Does it affect you
Names Fortinet FortiGate (FortiOS). Enter the product and version you run to place it against the affected range the vendor published.
What to do
- Follow the vendor advisory for the fixed release and any interim mitigation.
fortiguard.fortinet.com - Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
cisa.gov
CISA’s notes for this entry:
Affected, as published to NVD
- forti-os
- Fortinet FortiGate (FortiOS): 7.0.0 up to the fix in 7.0.22
The record
- NVD status
- Analyzed
- Published
- 09 Dec 2025, last modified 17 Jun 2026 (NVD)
- Severity
- CVSS 3.1 base score 9.8, Critical — computed here from the vector; NVD states 9.8.
- Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness
- CWE-347 Improper Verification of Cryptographic Signature (NVD; names by MITRE)
- Exploitation
- Listed in CISA’s Known Exploited Vulnerabilities catalogue since 16 Dec 2025; federal remediation due 23 Dec 2025. CISA entry
- Exploit probability
- EPSS 68.3%, 99th percentile — FIRST, scored 23 Oct 2026. FIRST EPSS
- Vendor
- Fortinet · Multiple Products (CISA)
References on the NVD record
- fortiguard.fortinet.com/psirt/FG-IR-25-647Vendor Advisory
- arcticwolf.com/resources/blog/arctic-wolf-observes-malicious-sso-logins-following-disclosure-cve-2025-59718-cve-2025-59719/Third Party Advisory
- cert-portal.siemens.com/productcert/html/ssa-864900.htmlThird Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-59718US Government Resource
Sources
The verdict above is computed from the products and versions you entered and the affected ranges the vendor published to NVD. It does not inspect your environment, and this site never reports a product as unaffected: why.