CVE-2025-59718

Fortinet Multiple Products Improper Verification of Cryptographic Signature

9.8 CRITICALActively exploited (CISA KEV)EPSS 68.3%

Published9 Dec 2025
Added to CISA KEV16 Dec 2025
Remediation due23 Dec 2025

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.

Added to KEV: 16 Dec 2025Federal remediation due: 23 Dec 2025

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 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Fortinet FortiProxy≥ 7.0.0 < 7.0.22 · ≥ 7.2.0 < 7.2.15 · ≥ 7.4.0 < 7.4.11 · ≥ 7.6.0 < 7.6.4

Fortinet Fortiswitchmanager≥ 7.0.0 < 7.0.6 · ≥ 7.2.0 < 7.2.7

Fortinet FortiOS≥ 7.0.0 < 7.0.18 · ≥ 7.2.0 < 7.2.12 · ≥ 7.4.0 < 7.4.9 · ≥ 7.6.0 < 7.6.4

Siemens Ruggedcom Ape1808 Firmwareall versions

Remediation

Fixed in

Fortinet FortiProxy≥ 7.0.22

Fortinet Fortiswitchmanager≥ 7.0.6

Fortinet FortiOS≥ 7.0.18

Patch & vendor advisories

https://fortiguard.fortinet.com/psirt/FG-IR-25-647

References

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://fortiguard.fortinet.com/psirt/FG-IR-25-647Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-59718US Government Resource

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2025-59718 being actively exploited?

Yes. CVE-2025-59718 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 16 Dec 2025.

How severe is CVE-2025-59718?

CVE-2025-59718 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 68.3% probability of exploitation.

Which products are affected by CVE-2025-59718?

Affected products include Fortinet FortiProxy, Fortinet Fortiswitchmanager, Fortinet FortiOS, Siemens Ruggedcom Ape1808 Firmware.

How do I fix CVE-2025-59718?

Upgrade affected software to a fixed version, for example Fortinet FortiProxy 7.0.22, Fortinet Fortiswitchmanager 7.0.6, Fortinet FortiOS 7.0.18 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-59718 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.