CVE-2026-41269: Flowise: File Upload Validation Bypass in createAttachment

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-23 · updated 2026-10-26
Weakness: CWE-434

Description

Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.0, the Chatflow configuration file upload settings can be modified to allow the application/javascript MIME type. This lets an attacker upload .js files even though the frontend doesn’t normally allow JavaScript uploads. This enables attackers to persistently store malicious Node.js web shells on the server, potentially leading to Remote Code Execution (RCE). This vulnerability is fixed in 3.1.0.

Affected products

FlowiseAI Flowise: before 3.1.0 — fixed in 3.1.0

How to fix

Upgrade to a fixed version: FlowiseAI Flowise 3.1.0. Check the vendor advisory for mitigations.

References

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