ENH: Exploit module for Langflow Authenticated Remote Code Execution vulnerability CVE-2026-18729

[rmhowe425]

Description

This pull request adds a new exploit module that detects and exploits an authenticated remote code execution vulnerability impacting Langflow versions 1.11.1 and below

Related Issue:
Fixes #21847

Breaking Changes

None

Reviewer Notes

Verification Steps

1. docker pull and docker run langflow, per documentation
2. Start msfconsole
3. Do: use exploit/multi/http/langflow_auth_rce_cve_2026_18729
4. Do: run lhost=<lhost> rhost=<rhost> username=<username> password=<password>
5. Do: exploit
6. You should get a meterpreter session

Test Evidence

Environment

Field	Details
Operating System	Ubuntu 22.04
Target Software/Hardware	langflow 1.10.0
Docker Image / Vagrant Setup	langflowai/langflow:1.10.0

AI Usage Disclosure

None

Pre-Submission Checklist

• Included a corresponding documentation markdown file in documentation/modules (new modules only)
• No sensitive information (IP addresses, credentials, API keys, hashes) in code or documentation
• Tested on the target environment specified in the Environment section above
• Included RSpec tests for library changes (encouraged for lib/ changes)
• Read the CONTRIBUTING.md and module acceptance guidelines

[rmhowe425]

@bwatters-r7 when I fire this exploit I am consistently getting 3 meterpreter shells almost instantly. After a day of debugging I believe I know why.

The purpose of the api/v1/custom_component endpoint is to take Python source code for a custom component, send it to the Langflow backend, have Langflow parse/validate/instantiate the component, and return the resulting component/node information.

On the backend there is a bunch of post-processing that occurs and executes the payload multiple times. From much debugging, this appears to be the control flow that is causing multiple meterpreter sessions.

Are we okay with multiple meterpreter sessions being created?

/api/v1/custom_component
|
v
custom component API handler
|
v
Component(_code=)
|
v
build_custom_component_template(...)
|
v
eval_custom_component_code(...)
|
v
validate.create_class(...)
|
+--> compile(...)
|
+--> exec(...)
|
v
Created Component class
|
v
Inspect inputs / outputs / metadata
|
v
Build component template/node
|
v
Return node definition

[rmhowe425]

Further evidence on the above: