CVE-2026-55856: MariaDB-Corporation MariaDB-Connector-J

Medium severity, CVSS 5.9. EPSS: 0.4% chance of exploitation in the next 30 days.

MariaDB Connector/J is used to connect applications developed in Java to MariaDB and MySQL databases. Prior to 2.7.14, 3.3.5, 3.4.3, and 3.5.9, when a Java application connects with sslMode=verify-full or sslMode=verify-ca, supplies a password, and does not configure serverSslCert or trustStore, Connector/J can accept an untrusted self-signed certificate through the fallbackToSystemTrustStore=true ephemeral trust manager and record its certFingerprint for later identity binding. The OK-packet and authentication-switch paths enforce the certificate fingerprint, but the initial-handshake path does not. HandshakeResponse.encode() can therefore build and send a mysql_clear_password response before checking certFingerprint != null && !isMitMProof(), sslMode, or whether the authentication plugin is resistant to a man-in-the-middle, and the initial path also bypasses restrictedAuth. An active man-in-the-middle or hostile server can present a self-signed certificate, claim to be MariaDB, select mysql_clear_password as the initial authentication plugin, and receive the full database password before the connection is rejected. This issue is fixed in versions 2.7.14, 3.3.5, 3.4.3, and 3.5.9.

Affected products

• MariaDB-Corporation MariaDB-Connector-J: before 2.7.14 (fixed in 2.7.14); from 3.0.0, before 3.3.5 (fixed in 3.3.5); from 3.4.0, before 3.4.3 (fixed in 3.4.3); from 3.5.0, before 3.5.9 (fixed in 3.5.9)

Published 2026-08-28. Last modified 2026-09-08.