Flowise: File Upload Validation Bypass in createAttachment

published 2026-04-16 6 mo ago modified 2026-10-26 13 d ago also GHSA-rh7v-6w34-w2rr , EUVD-2026-25286

cvss: 7.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits: 0; none known

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.

Patch / fix

fixed in 2

npm flowise 3.1.0
flowiseai flowise 3.1.0

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 6 mo ago (2026-04-24)

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-rh7v-6w34-w2rr referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
NVD	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
GitHub	3.1	7.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	flowise	<3.1.0	3.1.0

Affected products

FlowiseAI Flowise

Classification

Weakness

CWE-434 Unrestricted Upload of File with Dangerous Type

References

github.com /FlowiseAI/Flowise/security/advisories/GHSA-rh7v-6w34-w2rr
exploit, web, vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2026-41269
advisory
github.com /FlowiseAI/Flowise
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary