Background exploitation KEV catalog No authentication

CVE-2025-59718

Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability

CheckOps priority index

8.1/10 Patch within 24 h

Severity9.1

Probability6.8

Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 68.3% higher than 99.3% of CVEs

CVSS 3.1 9.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:

Exploited for 322 days 16 Dec 2025

CISA due date 23 Dec 2025 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

KEV catalog (CISA)16 Dec 2025
Exploited in EUVD (ENISA)16 Dec 2025
Used by ransomwareno
EPSS above 10 %68.3%
No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

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

FortiOSFortiProxyFortiSwitchManagerMultiple Products

Affected versions

7.0.0 ≤7.0.17
7.6.0 ≤7.6.3
7.4.0 ≤7.4.8
7.0.0 ≤7.0.21
7.2.0 ≤7.2.14
7.2.0 ≤7.2.11
7.0.0 ≤7.0.5
7.4.0 ≤7.4.10
7.2.0 ≤7.2.6

Weaknesses (CWE)

CWE-347

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

09 Dec 2025
Published
16 Dec 2025
Exploitation reported (ENISA)
16 Dec 2025
Added to the KEV catalog
23 Dec 2025
CISA remediation due date
25 Sept 2026
EPSS peak: 68.3%

References

Other exploited vulnerabilities from the same vendor

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CVE-2025-68686Fortinet FortiOS Exposure of Sensitive Information to an Unauthorized Actor Vulnerability
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CVE-2026-39808Fortinet FortiSandbox OS Command Injection Vulnerability
8.8 · Actively exploited
CVE-2026-25089Fortinet FortiSandbox OS Command Injection Vulnerability
8.3 · Actively exploited