CVE-2026-90535
Received Received - Intake

Unauthenticated DoS in Flowise via Chatflow Abort

Publication date: 2026-09-12

Last updated on: 2026-09-12

Assigner: VulnCheck

Description
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.

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Meta Information

Published
2026-09-12
Last Modified
2026-09-12
Generated
2026-09-12
AI Q&A
2026-09-12
EPSS Evaluated
N/A
NVD
CVE-2026-90535
EUVD
EUVD-2026-76853

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
flowiseai flowise to 3.1.4 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

Attack-Flow Graph

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Executive Summary

CVE-2026-90535 is an unauthenticated denial of service vulnerability in Flowise versions before 3.1.4. It affects the /api/v1/text-to-speech/abort endpoint which accepts user-supplied chatflowId and chatId without verifying ownership. Attackers can terminate active chatflow predictions for any user by submitting requests with known identifiers, causing service disruption.

Detection Guidance

Monitor network traffic for repeated POST requests to the /api/v1/text-to-speech/abort endpoint with arbitrary chatflowId and chatId values. Check server logs for unusual abort events or disruptions in active chatflow predictions.

Impact Analysis

This vulnerability allows attackers to disrupt services by terminating active chatflow predictions without authentication. It can cause targeted denial of service, persistent disruption, and potential UI issues via Server-Sent Events. Automated attacks can continuously disrupt predictions.

Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling unauthorized service disruption. The unauthenticated denial of service allows attackers to terminate active chatflow predictions, which may interfere with data processing operations or protected health information handling. Such disruptions could violate availability requirements under GDPR Article 32 and HIPAA Security Rule standards for ensuring access to electronic protected health information.

Mitigation Strategies

Upgrade Flowise to version 3.1.4 or later to address the vulnerability. If immediate upgrade is not possible, restrict access to the /api/v1/text-to-speech/abort endpoint via network-level controls or disable unauthenticated access.

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