Claude AI assistant is one calendar invite away from total system compromise

Hacking now is as simple as sending a calendar invite. Security researchers have discovered a critical vulnerability in Claude Desktop Extensions that allows attackers to take over the system without any user interaction.

Cybernews previously warned about Claude Desktop browsing the internet and executing prompts embedded on untrusted websites.

Now, security researchers at LayerX Security have demonstrated another attack that is even easier to pull off. Instead of hoping an AI agent stumbles onto a malicious website, hackers can deliver instructions directly to the user's inbox.

“A single Google Calendar event can silently compromise a system running Claude Desktop Extensions. The flaw impacts more than 10,000 active users and 50 Claude Desktop Extensions,” LayerX warns in a report detailing the discovered remote code execution vulnerability.

The exploit is remarkably simple and doesn’t require any prompt engineering, obfuscation, or instruction hiring.

The demonstrated Google Calendar invite was titled “Task Management” and contained instructions as straightforward as they get: pull the package from GitHub, save it locally, and execute a specified file.

If the user ever prompts its Claude AI assistant to check the latest events in Google Calendar and handle them, Claude assumes that this command justifies running the code.

“This requires no user interaction, no confirmation prompt, and no explicit request for system-level automation. The result is a full remote code execution, meriting a CVSS score of 10/10,” LayerX said.

At the time of writing, this vulnerability remains unaddressed.

Claude roams unrestricted

Claude Desktop is an app for using Anthropic’s AI assistant directly on the computer instead of a web browser. Moreover, users can choose to grant the AI assistant greater access and capabilities, such as reading messages or controlling the browser, through the so-called Claude Desktop Extensions. That’s where the vulnerability lies.

Unlike traditional browser extensions, which are sandboxed, Claude Desktop Extensions run with full system permissions. They can read arbitrary files, access stored credentials, modify system settings, and execute commands.

Claude autonomously decides which installed tool to use, or how to best chain them together.

“As a result, Claude can autonomously chain low-risk connectors (e.g., Google Calendar) to high-risk local executors, without user awareness or consent,” LayerX explains.

“If exploited by a bad actor, even a benign prompt coupled with a maliciously worded calendar event is sufficient to trigger arbitrary local code execution that compromises the entire system.”

The researchers warn that there are no hardcoded safeguards preventing the AI assistant from misbehaving.

“Our recommendation is straightforward: until meaningful safeguards are introduced, MCP connectors should not be used on systems where security matters,” LayerX concludes.

This architectural design is not unique to Claude Desktop, and other local AI assistants with direct access and broad permissions may also be susceptible to similar exploits.

Unlock more exclusive Cybernews content on YouTube.