GHSA-hp74-gm6m-2qm5

# Reauthentication Bypass via One-Time Access Token Login ## Summary A weaker authentication method (OTA token or signup token) is accepted as passkey step-up proof, yielding unauthorized renewable 30-day OIDC refresh tokens for clients explicitly configured with `RequiresReauthentication: true`. The `POST /api/webauthn/reauthenticate` endpoint's access-token fallback checks only JWT freshness (`IssuedAt` within 60 seconds), not the authentication method used. The session cookie gate is also non-validating -- any arbitrary cookie value (e.g. `session=deadbeef`) is accepted, collapsing the reauth boundary to token recency alone. The bypass needs to succeed only once. The resulting OIDC grant includes a 30-day refresh token that can be rotated indefinitely, providing persistent victim-impersonation access to the protected downstream service. The attacker obtains `access_token` (1-hour TTL), `id_token` (victim's name, email, profile), and `refresh_token` (30-day TTL, renewable) for a client that was explicitly configured to require passkey step-up authentication. The attacker can perform victim-scoped actions at the downstream relying party indefinitely. ## Root Cause `CreateReauthenticationTokenWithAccessToken` (webauthn_service.go:362-403) only checks that the access token's `IssuedAt` claim is less than 60 seconds old: ```go // webauthn_service.go:378-381 tokenExpiration, ok := token.IssuedAt() if !ok || time.Since(tokenExpiration) > time.Minute { return "", &common.ReauthenticationRequiredError{} } ``` It does not check HOW the user originally authenticated. The `reauthenticateHandler` (webauthn_controller.go:179-207) falls into this path whenever the request body cannot be parsed as a WebAuthn credential assertion: ```go // webauthn_controller.go:189-199 credentialAssertionData, err := protocol.ParseCredentialRequestResponseBody(c.Request.Body) if err == nil { token, err = wc.webAuthnService.CreateReauthenticationTokenWithWebauthn(...) } else {