CVE-2026-55858 MariaDB Connector/J: Inappropriate Encoding for Output Context in org.mariadb.jdbc:mariadb-java-client
A character set mismatch in MariaDB Connector/J allows attackers to bypass escaping mechanisms, potentially leading to SQL injection or data corruption.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55858?
CVE-2026-55858 is a medium-severity SQL injection vulnerability in mariadb-corporation mariadb-connector-j, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-838
Which versions are affected by CVE-2026-55858?
8 open source packages ship an affected version, including org.mariadb.jdbc:mariadb-java-client.
| Package | Affected | Fixed in |
|---|---|---|
org.mariadb.jdbc:mariadb-java-client Maven | All versions | 2.7.14 |
org.mariadb.jdbc:mariadb-java-client Maven | All versions | 2.7.14 |
org.mariadb.jdbc:mariadb-java-client Maven | From 3.0.0 | 3.3.5 |
org.mariadb.jdbc:mariadb-java-client Maven | From 3.0.0 | 3.3.5 |
org.mariadb.jdbc:mariadb-java-client Maven | From 3.4.0 | 3.4.3 |
org.mariadb.jdbc:mariadb-java-client Maven | From 3.4.0 | 3.4.3 |
2 more packages
org.mariadb.jdbc:mariadb-java-client Maven | From 3.5.0 | 3.5.9 |
org.mariadb.jdbc:mariadb-java-client Maven | From 3.5.0 | 3.5.9 |
How do I fix CVE-2026-55858?
Upgrade org.mariadb.jdbc:mariadb-java-client to a fixed version for your release line: 2.7.14, 3.3.5, 3.4.3 or 3.5.9.
Use parameterised queries everywhere and never build SQL by joining strings. Upgrade affected software first; a web application firewall only buys time. More about SQL injection.
Is CVE-2026-55858 being exploited?
There is no known exploitation of CVE-2026-55858 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-GM04260, CLEANSTART-2026-JW77744, CLEANSTART-2026-KS34405, CLEANSTART-2026-VV64101, ECHO-2abe-4d67-0f4b, GHSA-xvr9-35cr-46v9 and 15 more.