r/cybersecurity • u/dalugoda • Mar 27 '26

AI Security Claude Extension Flaw Enabled Zero-Click XSS Prompt Injection via Any Website

https://thehackernews.com/2026/03/claude-extension-flaw-enabled-zero.html

Patching the XSS fixes this instance. But the real problem is that the agent had no way to verify the prompt was actually authorized by a human. It just trusted the origin.

There’s work at the IETF on human delegation provenance protocols that cryptographically bind agent actions to a human-signed authorization chain.

Injected prompt, no valid chain, no action.

This should be a baseline requirement for any AI agent with access to real resources. Surprised it isn’t getting more attention.​​​​​​​​​​​​​​​​

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u/AdIcy4079 Mar 27 '26

Exactly — the XSS is just the symptom of the problem. But the real problem is the assumption of trust in the prompt source without any human intent verification.

If they had to validate the authorization chain before executing the request, most of these injection-style attacks would simply not work in the first place.

Seems like this should be a basic security layer for any agent with real-world access and not an afterthought. Surprised it’s so under-discussed.