Book page text, count, and author/title length is not limited in PocketMine-MP

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Impact Players can fill book pages with as many characters as they like; the server does not check this. In addition, the maximum of 50 pages is also not enforced, meaning that players can create "book bombs". This causes a variety of problems: - Oversized NBT on the wire costing excess bandwidth for server and client - Server crashes when saving region-based worlds due to exceeding maximum chunk size of 1 MB (PM3-specific) - Server crashes if any book page exceeds 32 KiB (due to TAGString size limit) (PM4-specific) This does, however, require that an attacker obtain a writable book in the first place in order to exploit the problem. Patches The bug has been fixed in 3.26.5 and 4.0.5. Workarounds Ban writable books, or use a plugin to cancel PlayerEditBookEvent to cancel the event if strlen(text) 1024 || mbstrlen(text) 256. For more information If you have any questions or comments about this advisory: Email us at team@pmmp.io

Published by the source

6 Jan 2022, 23:53 UTC

Last modified by the source

11 Jan 2023, 05:03 UTC

Source last checked

26 Oct 2026, 13:56 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-p62j-hrxm-xcxf

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# Patch Next advisory brief: GHSA-p62j-hrxm-xcxf

Advisory: Book page text, count, and author/title length is not limited in PocketMine-MP
IDs: GHSA-p62j-hrxm-xcxf
Record: https://patchnext.com/advisories/ghsa-p62j-hrxm-xcxf (revision 1, source checked 26 Oct 2026, 13:56 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
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 4.0.5, 3.26.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist pocketmine/pocketmine-mp: affected < 3.26.5; >= 4.0.0, < 4.0.5; fixed in 3.26.5, 4.0.5

## 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-p62j-hrxm-xcxf (GitHub-reviewed advisory GHSA-p62j-hrxm-xcxf lists affected ranges: Packagist pocketmine/pocketmine-mp >=0 =4.0.0 <4.0.5)

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