# CVE-2026-55856

## Summary

- **CVE ID:** CVE-2026-55856
- **Severity:** MEDIUM
- **CVSS Score:** 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)
- **CWE:** CWE-522
- **Published:** Aug 28, 2026
- **Last Modified:** Aug 31, 2026

## 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, when a Java application connects with sslMode=verify-full or sslMode=verify-ca, supplies a password, and does not configure serverSslCert or trustStore, Connector/J can accept an untrusted self-signed certificate through the fallbackToSystemTrustStore=true ephemeral trust manager and record its certFingerprint for later identity binding. The OK-packet and authentication-switch paths enforce the certificate fingerprint, but the initial-handshake path does not. HandshakeResponse.encode() can therefore build and send a mysql_clear_password response before checking certFingerprint != null && !isMitMProof(), sslMode, or whether the authentication plugin is resistant to a man-in-the-middle, and the initial path also bypasses restrictedAuth. An active man-in-the-middle or hostile server can present a self-signed certificate, claim to be MariaDB, select mysql_clear_password as the initial authentication plugin, and receive the full database password before the connection is rejected. This issue is fixed in versions 2.7.14, 3.3.5, 3.4.3, and 3.5.9.

## Affected Products

- mariadb-corporation — mariadb-connector-j (< 2.7.14)
- mariadb-corporation — mariadb-connector-j (>= 3.0.0, < 3.3.5)
- mariadb-corporation — mariadb-connector-j (>= 3.4.0, < 3.4.3)
- mariadb-corporation — mariadb-connector-j (>= 3.5.0, < 3.5.9)

## References

- [CNA](https://github.com/mariadb-corporation/mariadb-connector-j/security/advisories/GHSA-g9jj-cgmh-9f38)
- [CNA](https://github.com/mariadb-corporation/mariadb-connector-j/commit/149ec6a626376214966c01f42d48be1b80d06056)
- [CNA](https://github.com/mariadb-corporation/mariadb-connector-j/commit/d90b9872322c76b05a48219be66bff1d33102f8a)
- [CNA](https://hackerone.com/reports/3777370)
- [CNA](https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/3.4.3)
- [CNA](https://github.com/mariadb-corporation/mariadb-connector-j/releases/tag/3.5.9)
- [CNA](https://jira.mariadb.org/browse/CONJ-1325)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.22%
- **EPSS Percentile:** 12.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-12._