Relyra SAML SignatureValue not cryptographically verified -> authentication bypass

Summary

Relyra 1.0.0 and 1.1.0 accept forged SAML signatures because SignatureValue was not cryptographically verified before the library returned a successful authentication result.

Details

In 1.0.0 and 1.1.0, the XMLDSig trust boundary was incomplete. :public_key.verify over the exclusive-C14N canonicalized SignedInfo was not performed against the configured IdP certificate's public key, DigestValue was not recomputed over the canonicalized referenced element, and canonicalize/2 remained an unused passthrough in the signature-verification path. The result was a structure-only acceptance path where document shape and trust-source rejection could succeed without proving the signature bytes.

Impact

A forged SignatureValue carrying an attacker-controlled NameID can be accepted as {:ok}. Any relying-party application using Relyra 1.0.0 or 1.1.0 can be logged into as an arbitrary user if it trusts the affected response path.

Patches

Relyra 1.2.0 closes the gap with real exclusive-C14N canonicalization, :public_key.verify against the configured IdP certificate's public key, and a constant-time DigestValue recompute/compare bound to the exact consumed node on both verify/4 and verify_metadata_root/4.

Workarounds

There is no safe configuration of 1.0.0 or 1.1.0. Upgrade to 1.2.0 or later.

Resources

• Fix commit 2e45689 (wire real XMLDSig crypto into the candidate arm)
• Fix commit 8910200 (close metadata trust bypass, pin over DER)
• Regression proof: test/security/xml/adversarial_crypto_test.exs, test/relyra/metadata/auto_refresh_test.exs, test/security/ci_gate_integrity_test.exs