Vulnerability in Mariadb-Corporation Mariadb-Connector-J

CVE-2026-55858

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.009 (57.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 57.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-55858: rose from 0.003 to 0.009.

EPSS over last 30 days · oldest: 0.003 · newest: 0.009 · change: +0.005

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-55858?
CVE-2026-55858 is a medium-severity vulnerability in Mariadb-Corporation Mariadb-Connector-J, classified under CWE-838. CVSS score: 5.9/10. Published 2026-08-28.
How severe is CVE-2026-55858?
Medium severity. CVSS v3 base score is 5.9 out of 10.