PocketMine-MP has LogDoS by many junk properties in client data JWT in LoginPacket

Exploitation

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

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Impact Attackers can fill the body of the clientData JWT in LoginPacket with lots of junk properties, causing the server to flood warning messages, as well as wasting CPU time. This happens because the JsonMapper instance used to process the JWT body is configured to warn on unexpected properties instead of rejecting them outright. While this behaviour increases flexibility for random changes introduced by Microsoft, it also creates vulnerabilities if not handled carefully. This vulnerability affects PocketMine-MP servers exposed to a public network where unknown actors may have access. Patches This issue was fixed in c1d4a813fb8c21bfd8b9affd040da864b794df71 by restricting the number of unknown properties to 10, and rejecting the packet if this limit is exceeded. This continues to tolerate random additions to the JWT between versions, while preventing the logger from being abused by clients to slow down the server. Workarounds Plugins can handle DataPacketReceiveEvent to capture…

Published by the source

15 Apr 2026, 19:43 UTC

Last modified by the source

15 Apr 2026, 19:43 UTC

Source last checked

26 Oct 2026, 14:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xp4f-g2cm-rhg7

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# Patch Next advisory brief: GHSA-xp4f-g2cm-rhg7

Advisory: PocketMine-MP has LogDoS by many junk properties in client data JWT in LoginPacket
IDs: GHSA-xp4f-g2cm-rhg7
Record: https://patchnext.com/advisories/ghsa-xp4f-g2cm-rhg7 (revision 1, source checked 26 Oct 2026, 14:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pocketmine/pocketmine-mp 5.42.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist pocketmine/pocketmine-mp: affected < 5.42.1; fixed in 5.42.1

## Suggested inspection (read-only)
- Packagist pocketmine/pocketmine-mp: 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 pocketmine/pocketmine-mp.
- 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-xp4f-g2cm-rhg7 (GitHub-reviewed advisory GHSA-xp4f-g2cm-rhg7 lists affected ranges: Packagist pocketmine/pocketmine-mp >=0 <5.42.1)

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