Medium [CVE-2026-53712] Authentication downgrade via TLS man-in-the-middle attack

SCRAM (Salted Challenge Response Authentication Mechanism) is part of the family of Simple Authentication and Security Layer (SASL, RFC 4422) authentication mechanisms.

Prior to 3.3, a flaw in com.ongres.scram:scram-client and com.ongres.scram:scram-common allows an attacker capable of a TLS man-in-the-middle attack to silently downgrade a connection from SCRAM-SHA-256-PLUS with channel binding to standard SCRAM-SHA-256 without channel binding when TlsServerEndpoint processes an X.509 certificate using a modern signature algorithm such as Ed25519; getChannelBindingData() can return an empty byte array after NoSuchAlgorithmException, and the ScramClient builder treats that as absent channel-binding data.

This issue is fixed in version 3.3. This vulnerability allows the attacker to bypass the stronger SCRAM-SHA-256-PLUS authentication with channel binding, forcing a weaker SCRAM-SHA-256 authentication without channel binding, which could compromise the integrity of the authentication.

While requiring a sophisticated network attack, successful exploitation bypasses stronger channel-bound authentication, potentially compromising the integrity of user sessions. Red Hat severity: Moderate — CVSS 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N).

Weakness: CWE-303.