Researchers showed Claude's web-fetch tool could be tricked into leaking private data — Anthropic has patched it

A security researcher found that Claude's web-fetch tool would follow URLs embedded in previously fetched pages — not just links the user provided — enabling a nested-link chain that could exfiltrate private data such as conversation memories to attacker-controlled sites. Anthropic patched the flaw after disclosure, and security firm Oasis published an independent analysis of the attack chain.

What it means If your team gives AI tools web access, this is the canonical example of why fetched content must be treated as untrusted input — audit which of your tools can follow links they read.