CVE-2026-55857: MariaDB Connector/J: Cleartext Transmission of Sensitive Information and Insufficiently Protected Credentials

Vulnerability summary

CVE-2026-55857 is a medium (CVSS 5.9) vulnerability in mariadb-corporation mariadb-connector-j. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 33.2% of scored vulnerabilities.

Timeline

1. 28-08-2026
   PublishedVulnerability first disclosed.
2. 31-08-2026
   Last modifiedVulnerability information updated.

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, PAM dialog authentication can be coerced into transmitting the account password over an insecure connection. The mysql_clear_password plugin is gated behind a secure transport, but the sibling PAM handler SendPamAuthPacketFactory, named dialog by the server, does not declare that requirement and inherits the default secure-required value false; older branches implement the same affected behavior in SendPamAuthPacket. A hostile or man-in-the-middle server can send an Authentication Switch Request for dialog over plain TCP, causing the driver to return the user's password in cleartext when sslMode=DISABLE and restrictedAuth=null, which is the default configuration. Properly verified TLS and local Unix sockets are not exposed to this transport vector. This issue is fixed in versions 2.7.14, 3.3.5, 3.4.3, and 3.5.9.

• CWE-319Cleartext Transmission of Sensitive InformationThe product transmits sensitive or security-critical data in cleartext in a communication channel that can be sniffed by unauthorized actors.
• CWE-522Insufficiently Protected CredentialsThe product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.