The vulnerability in the ongress scram-client and scram-common libraries allows an attacker capable of a TLS Man‑In‑The‑Middle (MITM) attack to silently downgrade a channel‑binding enabled SCRAM‑SHA‑256‑PLUS connection to a plain SCRAM‑SHA‑256 connection without channel binding by causing the client to interpret the absence of channel binding data as missing binding data during certificate processing.

The affected software is com.ongres.scram:scram-client and com.ongres.scram:scram-common used by ongress scram implementations. All versions prior to 3.3 are vulnerable.

The CVSS v3 score is 8.2, indicating high severity while the EPSS score of less than 1% suggests a low likelihood of exploitation. The vulnerability is not listed in CISA KEV. An attacker would need a TLS MITM setup that can supply a modern signature algorithm such as Ed25519 in an X.509 certificate, which triggers the client to treat channel binding data as absent, effectively lowering authentication security.