MariaDB has cleartext password disclosure to a MITM on the initial-handshake

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-55856: 0.44% estimated exploitation activity in the next 30 days; percentile 38.54 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary When a Java application connects with sslMode=verify-full (or verify-ca) and a password but does not pin a server certificate, Connector/J deliberately accepts an untrusted/self-signed certificate at the TLS layer (the "MITM-proof without a CA" feature) and proves the server's identity afterwards by binding the certificate fingerprint into the authentication exchange. That fingerprint enforcement is applied to the OK-packet and auth-switch paths but not to the initial-handshake path. An active man-in-the-middle that presents a self-signed certificate, claims to be MariaDB, and names the initial authentication plugin mysqlclearpassword receives the victim's database password in cleartext, before any fingerprint/identity check runs. The connection is torn down a moment later, but the credential is already gone. Details For sslMode=verify-full/verify-ca with a password and no serverSslCert/trustStore, the connector falls back to an ephemeral trust manager (default…

Published by the source

28 Aug 2026, 22:41 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 16:55 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g9jj-cgmh-9f38

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-g9jj-cgmh-9f38

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# Patch Next advisory brief: CVE-2026-55856

Advisory: MariaDB has cleartext password disclosure to a MITM on the initial-handshake
IDs: CVE-2026-55856, GHSA-g9jj-cgmh-9f38
Record: https://patchnext.com/advisories/cve-2026-55856 (revision 2, source checked 26 Oct 2026, 16:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.mariadb.jdbc:mariadb-java-client 3.5.9, 3.4.3, 3.3.5, 2.7.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.mariadb.jdbc:mariadb-java-client: affected < 2.7.14; >= 3.0.0, < 3.3.5; >= 3.4.0, < 3.4.3; >= 3.5.0, < 3.5.9; fixed in 3.5.9, 3.3.5, 2.7.14, 3.4.3

## Suggested inspection (read-only)
- Maven org.mariadb.jdbc:mariadb-java-client: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.mariadb.jdbc:mariadb-java-client.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-g9jj-cgmh-9f38 (OSV record GHSA-g9jj-cgmh-9f38 lists affected ranges: Maven org.mariadb.jdbc:mariadb-java-client >=0 =3.0.0 =3.4.0 =3.5.0 <3.5.9 (fixed))
- Verified: https://github.com/advisories/GHSA-g9jj-cgmh-9f38 (GitHub-reviewed advisory GHSA-g9jj-cgmh-9f38 lists affected ranges: Maven org.mariadb.jdbc:mariadb-java-client >=0 =3.0.0 =3.4.0 =3.5.0 <3.5.9)

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