MariaDB Connector/J: Rogue server can drive large heap allocations from server-declared lengths in OK packets

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:N/I:N/A:H

EPSS

• CVE-2026-119276: 0.35% estimated exploitation activity in the next 30 days; percentile 28.80 (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 MariaDB Connector/J sized heap allocations from lengths declared by the server in OK packets before checking that those lengths fit in the packet. A rogue or MitM server can make the client allocate megabytes from a packet of a few bytes.

Details When `CLIENT_SESSION_TRACK` is negotiated (the default), an OK packet carries an info field followed by session-state blocks, each tracked variable being sent as a length-encoded name and value. `OkPacket.parse()` and `parseWithInfo()` allocated `new byte[len]` for the info field, the variable name and the value with the server-declared `len`, then copied the packet data into it. The copy failed with an `ArrayIndexOutOfBoundsException` when the packet was shorter, but only after the allocation had taken place. A server-declared length of 8 MiB in an 18-byte packet was enough to trigger an 8 MiB allocation; the integer-range validation of length-encoded values does not help, since such lengths are valid positive integers. The…

Published by the source

30 Oct 2026, 23:00 UTC

Last modified by the source

30 Oct 2026, 23:15 UTC

Source last checked

31 Oct 2026, 07:05 UTC

1. Revision 2 · amended · 31 Oct 2026

   Amended from osv record GHSA-h599-m3w5-9m7x

2. Revision 1 · created · 30 Oct 2026

   Published from ghsa record GHSA-h599-m3w5-9m7x

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# Patch Next advisory brief: CVE-2026-119276

Advisory: MariaDB Connector/J: Rogue server can drive large heap allocations from server-declared lengths in OK packets
IDs: CVE-2026-119276, GHSA-h599-m3w5-9m7x
Record: https://patchnext.com/advisories/cve-2026-119276 (revision 2, source checked 31 Oct 2026, 07:05 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 3.5.11, 3.4.5, 3.3.7. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.mariadb.jdbc:mariadb-java-client: affected >= 3.0.0, < 3.3.7; >= 3.4.0, < 3.4.5; >= 3.5.0, < 3.5.11; fixed in 3.5.11, 3.3.7, 3.4.5

## 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://github.com/advisories/GHSA-h599-m3w5-9m7x (GitHub-reviewed advisory GHSA-h599-m3w5-9m7x lists affected ranges: Maven org.mariadb.jdbc:mariadb-java-client >=3.0.0 =3.4.0 =3.5.0 <3.5.11)
- Verified: https://osv.dev/vulnerability/GHSA-h599-m3w5-9m7x (OSV record GHSA-h599-m3w5-9m7x lists affected ranges: Maven org.mariadb.jdbc:mariadb-java-client >=3.0.0 =3.4.0 =3.5.0 <3.5.11 (fixed))

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