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CVE-2026-55858— MariaDB Connector/J: Inappropriate Encoding for Output Context in org.mariadb.jdbc:mariadb-java-client

Quick assessment

Affected
mariadb-corporation mariadb-connector-j
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

MariaDB R2DBC connector是MariaDB基金会的一款关系数据库响应式连接器。 MariaDB R2DBC connector 2.7.14之前版本、3.0.0-alpha至3.3.5之前版本、3.4.0至3.4.3之前版本和3.5.0至3.5.9之前版本存在输出处理不当漏洞，该漏洞源于连接器对character_set_client参数处理不当，在服务器中途更改字符集后仍以UTF-8进行编码解码和转义，可能导致静默数据损坏并绕过字节级引用或转义。

CVSS 5.9 · Medium EPSS 0.87% · P58

Affected Version Matrix 4

VendorProduct Version RangeStatus
mariadb-corporation mariadb-connector-j < 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
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I. Basic Information for CVE-2026-55858

Vulnerability Information
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Vulnerability Title
MariaDB Connector/J: Inappropriate Encoding for Output Context in org.mariadb.jdbc:mariadb-java-client
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
输出上下文语义编码不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
MariaDB R2DBC connector 输出处理不当漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MariaDB R2DBC connector是MariaDB基金会的一款关系数据库响应式连接器。 MariaDB R2DBC connector 2.7.14之前版本、3.0.0-alpha至3.3.5之前版本、3.4.0至3.4.3之前版本和3.5.0至3.5.9之前版本存在输出处理不当漏洞，该漏洞源于连接器对character_set_client参数处理不当，在服务器中途更改字符集后仍以UTF-8进行编码解码和转义，可能导致静默数据损坏并绕过字节级引用或转义。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
mariadb-corporation mariadb-connector-j < 2.7.14 -

II. Public POCs for CVE-2026-55858

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III. Intelligence Information for CVE-2026-55858

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Patches & Fixes for CVE-2026-55858 (4)

Vendor Advisories for CVE-2026-55858 (1)

Vendor Pages for CVE-2026-55858 (4)

Other References for CVE-2026-55858 (1)

Same Patch Batch · mariadb-corporation · 2026-08-28 · 8 CVEs total

CVE-2026-55215 7.5 HIGH MariaDB Connector/Node.js: Connector leaks the cleartext password to an MitM despite `ssl:
CVE-2026-55855 6.5 MEDIUM MariaDB Connector/Node.js: Possible SQL injection in Buffer parameter escaping under big5/
CVE-2026-55854 5.9 MEDIUM MariaDB Connector/Node.js: Cleartext Transmission of Sensitive Information and Insufficien
CVE-2026-55856 5.9 MEDIUM MariaDB Connector/J: Cleartext password disclosure to a MITM on the initial-handshake
CVE-2026-55860 5.9 MEDIUM MariaDB Connector/R2DBC: Cleartext password disclosure to a man-in-the-middle server (clea
CVE-2026-55859 5.9 MEDIUM MariaDB Connector/R2DBC: Inappropriate Encoding for Output Context and Improper Encoding o
CVE-2026-55857 5.9 MEDIUM MariaDB Connector/J: Cleartext Transmission of Sensitive Information and Insufficiently Pr

IV. Related Vulnerabilities

Same product: mariadb-connector-j
Same vendor: mariadb-corporation
Same weakness: CWE-838

V. Comments for CVE-2026-55858

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