Relyra SAML SignatureValue not cryptographically verified -> authentication bypass
Date: 2026-06
Affected: erlang/relyra
Attack vector: auth-bypass
Category: vulnerability-disclosure
Severity: Critical
CVE: CVE-2026-49454
CWE: CWE-287
CWE-347
CVSS: 9.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N)

## 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 tr


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