Threats / Fortinet / CVE-2025-59718
CVE-2025-59718
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Fortinet Multiple Products vulnerability
Fortinet products contain improper cryptographic signature verification in SAML authentication, allowing unauthenticated attackers to bypass FortiCloud SSO login via crafted messages.
Verdict
Today item — known-exploited.
An unauthenticated remote attacker can forge SAML authentication tokens to bypass FortiCloud single sign-on protections across multiple Fortinet products. Active exploitation has been observed in the wild.
CISA KEV Yes · 2025-12-165EPSS 0.63018 (verify live)6CVSS 9.13CISA SSVC Exploitation: active · Automatable: yes · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
19 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-12-16).
Probability (EPSS)
EPSS 0.63018 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 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) · Affected: Fortinet, Multiple Products. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-347 CWE-347 — weakness family: Cryptography.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 7 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious SAML assertion with an invalid or forged cryptographic signature.
Business
Fortinet's authentication infrastructure fails to properly validate the signature, creating a direct path to unauthorized access.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I submit the forged SAML message to the FortiCloud SSO endpoint without valid credentials.
Business
The authentication system accepts the message due to signature verification bypass, granting me session access.
3
Lateral reach — past segmentation narrative 3
Attacker
I gain unauthenticated access to protected Fortinet management interfaces and cloud services.
Business
Attackers obtain administrative or user-level access to security appliances, enabling lateral movement and data exfiltration across the organization.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05