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.
MariaDB Connector/J: Inappropriate Encoding for Output Context in org.mariadb.jdbc:mariadb-java-client
Problem type
Affected products
mariadb-corporation
< 2.7.14 - AFFECTED
>= 3.0.0-alpha, < 3.3.5 - AFFECTED
>= 3.4.0, < 3.4.3 - AFFECTED
>= 3.5.0, < 3.5.9 - AFFECTED
References
https://github.com/mariadb-corporation/mariadb-connector-j/security/advisories/GHSA-xvr9-35cr-46v9
https://github.com/mariadb-corporation/mariadb-connector-j/commit/300716bef1e1d0370a41be7863b88aa2d55fbb69
https://github.com/mariadb-corporation/mariadb-connector-j/commit/7b3c69221b5463ee03472654040b3f6b9e5329c7
https://github.com/mariadb-corporation/mariadb-connector-j/commit/8cfd9df697372ad4ed09fe87a34b34babb6d43d6
https://github.com/mariadb-corporation/mariadb-connector-j/commit/c555c9b477521be0c35c3a5461f9f46681553607
https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/2.7.14
https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/3.3.5
https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/3.4.3
https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/3.5.9
https://jira.mariadb.org/browse/CONJ-1317
GitHub Security Advisories
GHSA-xvr9-35cr-46v9
org.mariadb.jdbc:mariadb-java-client has Inappropriate Encoding for Output Context
https://github.com/advisories/GHSA-xvr9-35cr-46v9Summary
The connector encodes and decodes all character data assuming the connection character set is UTF-8. A server can change character_set_client mid-session to a non-UTF-8 charset, after which the driver and server interpret the same bytes under different encodings, causing silent data corruption and a client/server charset-confusion mismatch.
Details
The driver encodes and decodes all character data on the assumption that the connection character set is UTF-8. Charset can be changed by commands like SET NAMES... commands.
If the new charset is not UTF-8, the driver continues to read and write UTF-8 while the server interprets the same bytes under a different encoding. The result is silent data corruption and a client/server charset-confusion mismatch. Charset confusion of this kind is also the primitive that can defeat byte-wise quoting/escaping when client and server disagree on a multi-byte encoding.
Impact
Silent data corruption and a client/server encoding mismatch once the connection's charset diverges from UTF-8. Because the mismatch undermines the assumption that quoting/escaping operates on UTF-8 bytes, it belongs to the charset-confusion class that can lead to SQL injection.
Patches
Fixed in 2.7.14, 3.3.5, 3.4.3, and 3.5.9. Upgrade to the patched release on your branch (3.5.x → 3.5.9, 3.4.x → 3.4.3, 3.0/3.1/3.2/3.3.x → 3.3.5, 2.x → 2.7.14). Once the connection is fully initialized, any subsequent charset change to a value that is not utf8 / utf8mb3 / utf8mb4 is rejected: the driver raises a SQLException with SQLState 08000 (connection exception) and closes the connection rather than continuing to exchange data under a mismatched encoding.
Workarounds
There is no reliable application-level workaround.
Credit
Reported by Yalguun Tumenkhuu (@fg0x0).
https://github.com/mariadb-corporation/mariadb-connector-j/security/advisories/GHSA-xvr9-35cr-46v9
https://github.com/mariadb-corporation/mariadb-connector-j/commit/300716bef1e1d0370a41be7863b88aa2d55fbb69
https://github.com/mariadb-corporation/mariadb-connector-j/commit/7b3c69221b5463ee03472654040b3f6b9e5329c7
https://github.com/mariadb-corporation/mariadb-connector-j/commit/8cfd9df697372ad4ed09fe87a34b34babb6d43d6
https://github.com/mariadb-corporation/mariadb-connector-j/commit/c555c9b477521be0c35c3a5461f9f46681553607
https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/2.7.14
https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/3.3.5
https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/3.4.3
https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/3.5.9
https://jira.mariadb.org/browse/CONJ-1317
https://github.com/advisories/GHSA-xvr9-35cr-46v9
JSON source
https://cveawg.mitre.org/api/cve/CVE-2026-55858Click to expand
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"assignerShortName": "GitHub_M",
"dateUpdated": "2026-08-28T22:46:40.114Z",
"dateReserved": "2026-06-17T16:44:40.995Z",
"datePublished": "2026-08-28T22:46:40.114Z",
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"title": "MariaDB Connector/J: Inappropriate Encoding for Output Context in org.mariadb.jdbc:mariadb-java-client",
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"metrics": [
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"attackComplexity": "HIGH",
"privilegesRequired": "NONE",
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"scope": "UNCHANGED",
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"baseScore": 5.9,
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}