Mittwald: German web host breached through its AI assistant connector (MCP server)

Top-Secured cyber watch: independent analysis based on the official statement of Mittwald and on the press. Top-Secured is not affiliated with this company and will never ask you for your bank details or passwords.

German hosting provider Mittwald disclosed on 7 November 2026 that an attacker got into its platform through the MCP server it offers so customers can connect AI assistants to its mStudio interface. The intruder stayed unnoticed from 27 October to 4 November; the company has shut the MCP server down, informed the authorities and is contacting affected customers.

What happened

Mittwald, a German hosting company whose customers are mostly web agencies, published an incident report on its blog on 7 November 2026, signed by its founder and managing director. The entry point was the MCP (Model Context Protocol) server that lets customers drive mStudio, its hosting management interface, from an AI assistant. According to the company’s timeline, the attacker first probed the flaw on 21 October, then behaved like an ordinary customer for a few days, opening test accounts and trying simple injections. On 27 October they registered a new account and exploited the weakness. Mittwald treats all data from that date onwards as compromised.

Detection and impact

Unusual activity was spotted on 4 November: the attacker’s first account was blocked, the MCP server was identified as the way in and switched off. On 5 November, Mittwald blocked the projects showing traces of the intruder, suspended new sign-ups, mStudio logins and SSH access, called in external forensic experts and informed the authorities. The company says 56 customer projects were compromised and that later scans found no further ones. mStudio and SSH were back on 7 November; websites blocked as a precaution stay offline for now. Mittwald believes the speed of the actions points to AI tools; according to The Record, it gave no other evidence. A detailed report is promised.

What to do now

1. Mittwald customers: read the company’s e-mails and status page, and check whether any of your projects is among those blocked.
2. Rotate the secrets stored in your projects since 27 October: database passwords, .env files, API keys, SSH keys, CMS administrator accounts.
3. Look for changes: unknown files, new admin users, modified cron jobs; compare with a backup taken before 21 October.
4. Enable passkeys on mStudio, now offered by Mittwald.
5. Inventory your own MCP connectors and AI integrations: limit their rights, give them dedicated tokens and log every call.

Our take

Any connector that lets an AI assistant act on your infrastructure is a new remote administration interface, and it deserves the same scrutiny as an API or a VPN. Give it least privilege, monitor it, and make sure you can switch it off in minutes.

Sources

• Mittwald — Sicherheitsvorfall am MCP-Server
• The Record — Cyberattack on German hosting provider Mittwald

How we choose, verify and write our analyses →