---
title: "CVE-2025-59718: Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability"
url: https://erroneo.us/security/cve/CVE-2025-59718/
description: "CVE-2025-59718 (Fortinet Multiple Products): Exploited in the wild (CISA KEV). A improper verification of cryptographic signature vulnerability in Fortinet…"
type: vulnerability-record
section: "Security Digest"
date_published: 2025-12-09
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-59718"
kev: true
cvss: 9.1
epss: 0.68293
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2025-59718: Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Fortinet Multiple Products. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2025-12-16, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2025-12-23 ; treat that as the outer limit, not the target.
- EPSS 68.3% , percentile 99: FIRST’s model estimates a 68.3% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Editorial verdict: Act now. FortiCloud SSO SAML Bypass: CVE-2025-59718/59719 — If any Fortinet device has FortiCloud SSO admin login turned on, it was open to unauthenticated admin takeover; upgrade, then also apply the January 2026 fix for CVE-2026-24858, which bypassed this patch.

## What it is

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.

## Affected products (CVE record)

- Fortinet FortiSwitchManager: 7.2.0 <= 7.2.6, 7.0.0 <= 7.0.5
- Fortinet FortiOS: 7.6.0 <= 7.6.3, 7.4.0 <= 7.4.8, 7.2.0 <= 7.2.11, 7.0.0 <= 7.0.17
- Fortinet FortiProxy: 7.6.0 <= 7.6.3, 7.4.0 <= 7.4.10, 7.2.0 <= 7.2.14, 7.0.0 <= 7.0.21

## Severity

- fortinet CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C`

## Exploitation

- CISA KEV: added 2025-12-16; federal due date 2025-12-23. Known ransomware use: Unknown.
- CISA required action: 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 SSVC assessment: exploitation active , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 68.29% probability of exploitation activity in the next 30 days; percentile 99.

## Sources

- [Listed in CISA KEV notes (fortiguard.fortinet.com)](https://fortiguard.fortinet.com/psirt/FG-IR-25-647)
- [Listed in CISA KEV notes (docs.fortinet.com)](https://docs.fortinet.com/upgrade-tool/fortigate)
- [CVE.org record CVE-2025-59718](https://www.cve.org/CVERecord?id=CVE-2025-59718)
- [NVD entry CVE-2025-59718](https://nvd.nist.gov/vuln/detail/CVE-2025-59718)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-59718)
- [arcticwolf.com](https://arcticwolf.com/resources/blog/arctic-wolf-observes-malicious-sso-logins-following-disclosure-cve-2025-59718-cve-2025-59719/)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/html/ssa-864900.html)

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Source page: https://erroneo.us/security/cve/CVE-2025-59718/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt