CVE-2026-55857

A flaw was found in MariaDB Connector/J. A remote attacker or a man-in-the-middle server can exploit a vulnerability in the PAM dialog authentication mechanism. This flaw allows the attacker to coerce the connector into transmitting account passwords over an insecure connection when default configurations are used. Consequently, the user's password can be intercepted in cleartext, leading to sensitive information disclosure.

MariaDB Connector/J (org.mariadb.jdbc:mariadb-java-client) can be coerced by a hostile or man-in-the-middle server into performing PAM 'dialog' authentication over an unencrypted connection, transmitting the account password in cleartext. The affected path (SendPamAuthPacketFactory/SendPamAuthPacket) does not require secure transport and is reachable under the default configuration (sslMode=DISABLE, restrictedAuth unset). Verified TLS (sslMode=verify-ca or verify-full) and local Unix-socket connections are not exposed. Red Hat rates the impact of this flaw as Moderate because exploitation requires a man-in-the-middle network position and a plaintext connection.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Connect using sslMode=verify-full (or verify-ca) with a properly configured server certificate and trust store, or use a local Unix socket, so the connector never negotiates PAM dialog authentication over cleartext. Setting restrictedAuth to exclude the dialog/mysql_clear_password plugins also prevents disclosure. A fixed MariaDB Connector/J (2.7.14, 3.3.5, 3.4.3, or 3.5.9, as appropriate for the branch in use) additionally addresses the issue.