Webauthn has a User Verification Downgrade via Default-Open ClientOverridePolicy
## Summary
In version 5.3.0 of the Symfony bundle, `Webauthn\Bundle\Policy\ClientOverridePolicy` defaulted to allowing all client overrides, including `userVerification`. A client could send `{"userVerification": "discouraged"}` in the assertion or attestation options request to override a server-configured `userVerification: required`, causing the emitted WebAuthn options to instruct the authenticator to skip user verification. The `CheckUserVerification` ceremony step then read the same downgraded options and skipped its check.
## Affected versions
- **Vulnerable**: 5.3.0
- **Patched**: 5.3.1
5.3.0 was released on 2026-05-01 and 5.3.1 w
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