CVE-2025-59718
Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability
Fortinet Multiple Products
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.
Ransomware groups exploiting CVE-2025-59718
Qilin ransomware was first observed in July of 2022. Qilin Ransomware is written in Golang and supports multiple encryption modes; all of which are controlled by the operator. Qilin actors practice double extortion – demanding payment for a decryptor, as well
Exploitation is attributed to these groups across their recorded activity. It does not follow that every organisation they listed was reached through CVE-2025-59718 — the source data does not record an entry point per incident.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 16 December 2025. US federal agencies were required to remediate it by 23 December 2025.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 68.3%, which is higher than 99.3% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Recent listings by these groups
Disclosures from the groups above, newest first.
Frequently asked questions
Is CVE-2025-59718 being exploited by ransomware groups?
Yes. CVE-2025-59718 is recorded as exploited by Qilin. Between them these groups account for 2,241 victim disclosures in this database.
What does CVE-2025-59718 affect?
CVE-2025-59718 affects Fortinet Multiple Products. 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.
How severe is CVE-2025-59718?
CVE-2025-59718 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 68.3%, higher than 99.3% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 23 December 2025.
How should organisations respond to CVE-2025-59718?
Apply the vendor patch for Fortinet Multiple Products as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.