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@acastellon/auth v2.2.0: validateToken() authentication bypass via spoofable headers

In @acastellon/auth v2.2.0, the validateToken() middleware has a service-to-service bypass that can be exploited by an unauthenticated attacker via spoofable au

19 Jun 2026Read 1 minSeverity: act now

What changed

In @acastellon/auth v2.2.0, the validateToken() middleware has a service-to-service bypass that can be exploited by an unauthenticated attacker via spoofable auth-user and Host headers, allowing authentication bypass.

Who it affects

All users of @acastellon/auth v2.2.0, especially those relying on validateToken() for route protection and downstream services trusting auth-user or is-* headers.

What to do today

Upgrade to v2.3.0+ immediately to remove the spoofable bypass and enforce mTLS-based service authentication.

The trail
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