AIKIDO-2026-458756

postgresql is vulnerable to Authentication Downgrade

Authentication DowngradeCVE-2026-54291 Published 5 days ago

Medium Risk

This Affects:

postgresql

42.7.4 - 42.7.11

Fixed in 42.7.12

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TL;DR

pgJDBC's SCRAM authenticator does not fully enforce channelBinding=require. When the bundled scram-client cannot derive a tls-server-end-point channel-binding hash from the server certificate (for example Ed25519, Ed448, or post-quantum signature algorithms), it supplies an empty binding instead of failing. pgJDBC then accepts negotiation to plain SCRAM-SHA-256 even though the connection was configured to require channel binding, silently removing the MITM protection that setting is meant to provide.

Who does this affect?

You are affected if you are using a version that falls within the vulnerable range and your JDBC connection properties set channelBinding=require. Connections using the default prefer policy, or allow / disable, are not affected because falling back to plain SCRAM is documented behavior for those modes.