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Response snapshot Oct 27, 2026, 03:06 UTC

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VulnerabilityCVE-2025-59718Known exploitation

Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability

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.

At a glance

Exploited
Yes: on CISA's Known Exploited list
Severity
9.1 Critical (CVSS 3.1)
Chance of exploitation
68.3% in the next 30 days
CISA federal deadline
Dec 23, 2025: passed
Sources
2 independent sources

What to do

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

Read CISA KEV entry CVE-2025-59718 (opens a new tab)

What happened

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.

CISA federal deadline

Federal due date passed

Applies to covered US federal agencies; it is not your organization's deadline.

Added to the catalog Known ransomware use: Unknown
CISA catalog (opens a new tab)

Scores and how they were measured

CVSS base severity

9.1

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

68.3%

Scored Percentile 99.3%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    CISA KEV entry CVE-2025-59718 (opens a new tab)

    The CVE-2025-59718 catalog entry establishes known exploitation, date added, required action, and the federal due date; not zero-day status.

    Published Checked

  2. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2025-59718, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

  3. Primary source

    CVE Program CNA fortinet (opens a new tab)

    The published CVE-2025-59718 document's CNA supplies this CVSS 3.1 base score, vector, and authoritative source update date.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2025, December 16). Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability (CVE-2025-59718). https://kevwire.com/record/CVE-2025-59718

MLA

"Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability (CVE-2025-59718)." KEVWire, 16 Dec. 2025, kevwire.com/record/CVE-2025-59718.

Chicago

KEVWire. "Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability (CVE-2025-59718)." Last modified December 16, 2025. https://kevwire.com/record/CVE-2025-59718.

Evidence summary (plain text)

Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability (Dec 16, 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.
CVSS 9.1 (version 3.1; evidence as of Mar 20, 2026; https://cveawg.mitre.org/api/cve/CVE-2025-59718).
EPSS 68.3% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2025-59718&date=2026-10-26).
Sources:
CISA KEV entry CVE-2025-59718: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2025-59718&date=2026-10-26
CVE Program CNA fortinet: https://cveawg.mitre.org/api/cve/CVE-2025-59718
Record ID: CVE-2025-59718.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Documented by a cited source.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
CISA federal due date: Dec 23, 2025. This is a deadline for covered US federal agencies, not the reader's SLA.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

CISA added this entry on 2025-12-16. This record's publication date is the catalog addition date, not necessarily the initial vulnerability disclosure. KEV means known exploitation, not necessarily a zero-day. CISA due dates apply to covered US federal agencies, not your organizational SLA.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

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