CVE-2026-55858: MariaDB-Corporation MariaDB-Connector-J

Medium severity, CVSS 5.9. EPSS: 0.9% 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, the connector encodes and decodes protocol text and performs client-side escaping under the assumption that the connection character set is UTF-8. The server can report a mid-session change to character_set_client through OK-packet session-state tracking, including a change caused by SET NAMES, a stored routine or trigger, server configuration, or a hostile server. If character_set_client changes to a non-UTF-8 value, the driver continues to read and write UTF-8 while the server interprets the same bytes under another encoding, causing silent data corruption and a client/server charset-confusion mismatch that can defeat byte-wise quoting or escaping. The fix accepts only utf8, utf8mb3, or utf8mb4 after initialization; any other value causes SQLException with SQLState 08000 and closes the connection. 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-alpha, 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.