BlackTreeCVE Intelligence
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Full vulnerability report · 2026
CVE-2026-90535High confidence

Flowise before 3.1.4 Denial of Service via text-to-speech/abort

FlowiseAI · Flowise

Official source article: GitHub GHSA-XHXX-56G3-MX2R ↗. Check the applicable product and release in the original source.

6.3MediumCVSS 4.0
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 14 Sep 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.48% 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.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs FlowiseAI Flowise 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 30 daysRemediation target: Within 180 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.

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-2026-76853

No EUVD known-exploited evidence

Flowise versions before 3.1.4 contain an unauthenticated denial of service vulnerability in the /api/v1/text-to-speech/abort endpoint that accepts user-supplied chatflowId and chatId without ownership verification. Attackers can terminate active chatflow predictions for any user by submitting requests with known chatflow and chat identifiers, causing targeted service disruption.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
6.3 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Flowise versions before 3.1.4 contain an unauthenticated denial of service vulnerability in the /api/v1/text-to-speech/abort endpoint that accepts user-supplied chatflowId and chatId without ownership verification. Attackers can terminate active chatflow predictions for any user by submitting requests with known chatflow and chat identifiers, causing targeted service disruption.

What

Flowise versions before 3.1.4 contain an unauthenticated denial of service vulnerability in the /api/v1/text-to-speech/abort endpoint that accepts user-supplied chatflowId and chatId without ownership verification. Attackers can terminate active chatflow predictions for any user by submitting requests with known chatflow and chat identifiers, causing targeted service disruption.

Why

The application reaches a protected operation without first confirming that the requester is authorised.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

Flowise versions before 3.1.4 contain an unauthenticated denial of service vulnerability in the /api/v1/text-to-speech/abort endpoint that accepts user-supplied chatflowId and chatId without ownership verification. Attackers can terminate active chatflow predictions for any user by submitting requests with known chatflow and chat identifiers, causing targeted service disruption.

Why

The application reaches a protected operation without first confirming that the requester is authorised.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

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.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Missing Authorization → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-862 ↗

CWE-862: Missing Authorization. The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: 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.ATPresentAttack requirements: A particular deployment or execution condition must be present.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VALowVulnerable-system availability: A successful attack can cause a limited loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
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.
NetworkUnauthenticatedDenial of serviceCWE-862Public exploit reference
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-76853Official EUVD mapping

Flowise versions before 3.1.4 contain an unauthenticated denial of service vulnerability in the /api/v1/text-to-speech/abort endpoint that accepts user-supplied chatflowId and chatId without ownership verification. Attackers can terminate active chatflow predictions for any user by submitting requests with known chatflow and chat identifiers, causing targeted service disruption.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3086Flowise: Mehrere Schwachstellen ermöglichen Umgehen von Sicherheitsvorkehrungen und DoS

Ein Angreifer kann mehrere Schwachstellen in Flowise ausnutzen, um Sicherheitsvorkehrungen zu umgehen und um einen Denial-of-Service-Zustand herbeizuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260916Security Bulletin 16 Sep 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 16 Sep 2026, published on 16 September 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-033738flowiseaiのflowiseにおける認証の欠如に関する脆弱性

Flowiseのバージョン3.1.4より前のバージョンには、認証なしで利用可能なサービス拒否（DoS）脆弱性が /api/v1/text-to-speech/abort エンドポイントに存在していました。このエンドポイントは、所有権の確認なくユーザーから提供されたchatflowIdおよびchatIdを受け入れます。攻撃者は既知のchatflowおよびchatIdを用いてリクエストを送信することで、任意のユーザーのアクティブなchatflow予測を強制的に終了させ、特定のサービスを妨害する可能性があります。

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.
Patch available
Affected
Flowise: 0 < 3.1.4
Fixed
Flowise: 3.1.4
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
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.
Official vendor articles1 stored document

Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.

04

Evidence and provenance

Published 12 Sept 2026 · Last source change 14 Sept 2026, 16:04 UTC · CWE-862 · Missing Authorization

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 2026-09-14
European sourceENISA EUVD · EUVD-2026-76853
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: github.com/GHSA-xhxx-56g3-mx2r.
    Before
    remediation: github.com/GHSA-xhxx-56g3-mx2r
    After
    remediation: github.com/GHSA-xhxx-56g3-mx2r · vendor advisory: github.com/GHSA-xhxx-56g3-mx2r
    github.com ↗
  2. Public exploit evidencePublic exploit evidence changed from Public exploit reference to Public exploit reference.
    Before
    Public exploit reference
    After
    Public exploit reference
    github.com ↗
  3. ENISA EUVD mappingEUVD-2026-76853 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-76853"}
    ENISA EUVD ↗
  4. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    CVE.org ↗
  5. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-76853↗CISA Vulnrichment SSVC evidence↗Public exploit reference · GitHub GHSA-XHXX-56G3-MX2R↗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-2026-90535 · cve.blacktree.nl