Claude Code Domain Validation Bypass Vulnerability Allowing Unconsented Web Requests

A domain validation bypass vulnerability has been identified in Claude Code versions prior to 1.0.111. The issue arises from inadequate URL validation in the trusted domain verification process for WebFetch requests. The application relied on a 'startsWith()' function for domain validation, which could be exploited by registering domains that appeared to be trusted but were actually controlled by attackers. This flaw could facilitate automatic requests to these malicious domains without user consent, potentially leading to unauthorized data access or exfiltration. The vulnerability has been patched in version 1.0.111.

Impact

Exploitation of this vulnerability could allow for unauthorized automatic requests to be sent to attacker-controlled domains, bypassing user consent and potentially leading to data exfiltration.

Remediation

Users on the standard Claude Code auto-update have already received the fix. Those performing manual updates should update to the latest version.