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Full vulnerability report · 2025
CVE-2025-59719High confidence

Fortinet FortiWeb — Improper Verification of Cryptographic Signature

Fortinet · FortiWeb

Official source articles: Siemens SSA-864900 ↗ · Fortinet FG-IR-25-647 ↗. Check the applicable product and release in the original source.

9.1CriticalCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 29.22% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Fortinet FortiWeb and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
SSA-864900 · CSAF 2.0 · revision 11 · finalSiemens ProductCERTSSA-864900: Multiple Vulnerabilities in Fortigate NGFW on RUGGEDCOM APE1808 Devices
1 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • RUGGEDCOM APE1808 with Fortinet NGFW < V7.4.9
Summary
An improper verification of cryptographic signature vulnerability in Fortinet FortiWeb 8.0.0, FortiWeb 7.6.0 through 7.6.4, FortiWeb 7.4.0 through 7.4.9 may allow an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML response message.
Remediation
Update Fortigate NGFW to V7.4.9 or later following the secure update recommendation procedure. Contact customer support to receive detailed information
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2025-202191

EU known exploited

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 27 Jan 2026. Evidence sources: eukev_kev.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

An improper verification of cryptographic signature vulnerability in Fortinet FortiWeb 8.0.0, FortiWeb 7.6.0 through 7.6.4, FortiWeb 7.4.0 through 7.4.9 may allow an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML response message.

What

An improper verification of cryptographic signature vulnerability in Fortinet FortiWeb 8.0.0, FortiWeb 7.6.0 through 7.6.4, FortiWeb 7.4.0 through 7.4.9 may allow an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML response message.

Why

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

An improper verification of cryptographic signature vulnerability in Fortinet FortiWeb 8.0.0, FortiWeb 7.6.0 through 7.6.4, FortiWeb 7.4.0 through 7.4.9 may allow an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML response message.

Why

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Verification of Cryptographic Signature → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-347 ↗

CWE-347: Improper Verification of Cryptographic Signature. The product does not verify, or incorrectly verifies, the cryptographic signature for data.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
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

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-347
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2025-2795Fortinet FortiOS, FortiProxy, FortiSwitch und FortiWeb: Schwachstelle ermöglicht Umgehen von Sicherheitsvorkehrungen

Ein Angreifer kann eine Schwachstelle in Fortinet FortiOS, Fortinet FortiProxy, Fortinet FortiSwitch und Fortinet FortiWeb ausnutzen, um Sicherheitsvorkehrungen zu umgehen.

Official advisory ↗
Canadian Centre for Cyber Security · English · AL26-014AL26-014 – FortiBleed leak of thousands of compromised credentials impacting Fortinet devices

An Alert is used to raise awareness of a recently identified cyber threat that may impact cyber information assets, and to provide additional detection and mitigation advice to recipients. The Canadian Centre for Cyber Security ("Cyber Centre") is also available to provide additional assistance regarding the content of this Alert to recipients as requested.

Official advisory ↗
Canadian Centre for Cyber Security · English · AL25-019AL25-019 - Vulnerabilities impacting Fortinet products - FortiCloud SSO Login Authentication Bypass - CVE-2025-59718 and CVE-2025-59719 - Update 2

An Alert is used to raise awareness of a recently identified cyber threat that may impact cyber information assets, and to provide additional detection and mitigation advice to recipients. The Canadian Centre for Cyber Security ("Cyber Centre") is also available to provide additional assistance regarding the content of this Alert to recipients as requested.

Official advisory ↗
Canadian Centre for Cyber Security · English · AV25-821Fortinet security advisory (AV25-821) – Update 1

On December 9, 2025, Fortinet published security advisories to address vulnerabilities in multiple products including two critical vulnerabilities (CVE-2025-59718, CVE-2025-59719): The FortiCloud SSO Login Authentication feature must be enabled on the affected products for these vulnerabilities to be exploited.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20251210Security Bulletin 10 Dec 2025

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 10 Dec 2025, published on 10 December 2025. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-1084Multiples vulnérabilités dans les produits Fortinet

De multiples vulnérabilités ont été découvertes dans les produits Fortinet. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, une élévation de privilèges et un déni de service à distance.

Official advisory ↗
CSIRT Italia · Italian · rilevato-possibile-sfruttamento-attivo-di-vulnerabilita-gia-note-in-prodotti-fortinetRilevato possibile sfruttamento attivo di vulnerabilità già note in prodotti Fortinet

Lo scorso dicembre, Fortinet ha rilasciato aggiornamenti di sicurezza finalizzati alla mitigazione delle vulnerabilità CVE-2025-59718 e CVE-2025-59719. Tuttavia, recenti osservazioni indicano che tali aggiornamenti potrebbero non risultare pienamente efficaci in specifici scenari. Sono stati infatti riscontrati possibili casi di bypass delle patch, caratterizzati da accessi SSO malevoli che consentirebbero la creazione di account amministrativi non autorizzati su dispositivi FortiGate, inclusi sistemi aggiornati all’ultima versione resa disponibile dal vendor. Al momento, queste evidenze sono in fase di analisi e non risultano ancora confermate ufficialmente da Fortinet. In particolare la non corretta risoluzione delle succitate vulnerabilità - di tipo “Authentication Bypass” con score CVSS v3.1 pari a 9.1 - già trattate nell’ambito del AL03/251210/CSIRT-ITA , consentirebbe a un attaccante remoto non autenticato, tramite risposte SAML opportunamente predisposte, di bypassare l’autenticazione FortiCloud SSO, ottenere accesso amministrativo e creare account non autorizzati sui dispositivi interessati.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2025-021534フォーティネットの Fortiweb におけるデジタル署名の検証に関する脆弱性

フォーティネットの Fortiweb には、デジタル署名の検証に関する脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6647美 CISA 발표 주요 Exploit 정보공유(Update. 2025-12-16)

우 긴급 패치를 권고 드립니다. * 참조 링크 : https://www.cisa.gov/known-exploited-vulnerabilities-catalog | cveID | vendorProject | vulnerabilityName | dateAdded | shortDescription | requiredAction | dueDate | | --- | --- | --- | --- | --- | --- | --- | | CVE-2025-59718 | Fortinet | Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability | 2025-12-16 | 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. | Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. | 2025-12-23 |

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6640Fortinet 제품 보안 업데이트 권고

FortiWeb에서 발생하는 인증우회 취약점(CVE-2025-59719) [1][3]

Official advisory ↗
NCSC-NL · Dutch · NCSC-2025-0386Kwetsbaarheden verholpen in Fortinet producten

De kwetsbaarheden stellen ongeauthenticeerde aanvallers in staat om toegang te krijgen tot de systemen door gebruik te maken van verschillende technieken, waaronder het omzeilen van FortiCloud SSO-login authenticatie via speciaal vervaardigde SAML-berichten, het behouden van actieve SSLVPN-sessies ondanks een wachtwoordwijziging, en het uitvoeren van ongeautoriseerde operaties via vervalste HTTP- of HTTPS-verzoeken. Dit kan leiden tot ongeautoriseerde toegang tot gevoelige API-gegevens en andere netwerkbronnen. **update 16-12-25**: Onderzoekers melden actief misbruik waar te nemen van de kwetsbaarheden met kenmerk CVE-2025-59718 en CVE-59719. Deze kwetsbaarheden stellen kwaadwillenden in staat om de Single Sign On te omzeilen en zo toegang te krijgen tot de kwetsbare systemen. De onderzoekers hebben Indicators of Compromise (IoC's) gepubliceerd om misbruik te kunnen onderzoeken. Het NCSC adviseert zo spoedig mogelijk de updates van Fortinet in te zetten, indien dit nog niet is gedaan, eventueel de mitigerende maatregelen in te zetten en middels de gepubliceerde IoC's te onderzoeken of misbruik heeft plaatsgevonden en op basis daarvan de administrator accounts het password van te roteren. Het NCSC adviseert aanvullend om te overwegen de open sessies van administrators te sluiten na inzet van de updates. Zie voor detailinformatie van de IoC's: https://arcticwolf.com/resources/blog/arctic-wolf-observes-malicious-sso-logins-following-disclosure-cve-2025-59718-cve-2025-59719/ **update 23-01-26**: De updates werken niet voldoende om te beschermen tegen de FortiCloud single sign-on (SSO) bypass kwetsbaarheden (CVE-2025-59718 en CVE-2025-59719). Er is misbruik van deze kwetsbaarheden waargenomen op systemen die de laatste updates hadden doorgevoerd. Zowel Fortinet als ArcticWolf hebben IoC's en mitigerende maatregelen ter beschikking gesteld. **update 28-01-26**: Bron CERT-AT bijgevoegd, bevat nieuwe IoC's voor onderzoek. Zie voor detailinformatie van de IoC's en mitigerende maatregelen: https://www.fortinet.com/blog/psirt-blogs/analysis-of-sso-abuse-on-fortios & https://arcticwolf.com/resources/blog/arctic-wolf-observes-malicious-configuration-changes-fortinet-fortigate-devices-via-sso-accounts/

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
RUGGEDCOM APE1808 with Fortinet NGFW < V7.4.9
Fixed
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 9 Dec 2025 · Last source change 11 Aug 2026, 12:23 UTC · CWE-347 · Improper Verification of Cryptographic Signature

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-202191
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Remediation statusRemediation status changed from Awaiting fix to Mitigation available.
    Before
    Awaiting fix
    After
    Mitigation available
    Siemens ProductCERT ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Remediation guidance recorded
ENISA EUVD · EUVD-2025-202191↗Siemens ProductCERT security advisory · Siemens SSA-864900↗CVE authority or vendor reference · Fortinet FG-IR-25-647↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2025-59719 · cve.blacktree.nl