# CVE-2022-51018: PocketMine-MP input validation bypass in book creation

Source: https://junglewise.ai/threats/cve-2022-51018-pocketmine-mp-input-validation-bypass-in-book-creation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-07. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2022-51018 · Severity: medium · CVSS 6.5 · Published 2026-09-07

PocketMine-MP is a Minecraft server implementation. The server fails to validate book content limits, allowing players to create oversized books ("book bombs") that consume excessive bandwidth and crash the server by exceeding data structure limits. An attacker must first obtain a writable book in-game to exploit this vulnerability.

Technologies: [pocketmine/pocketmine-mp (Packagist)](https://junglewise.ai/threats/technologies/pocketmine-pocketmine-mp). Vendors: [Packagist](https://junglewise.ai/threats/vendors/packagist).

## Quick answers

**Is CVE-2022-51018 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2022-51018 being exploited in the wild.

**How severe is CVE-2022-51018?** Medium severity, with a CVSS score of 6.5, published 7 September 2026.

**Which products and versions are affected?** pocketmine/pocketmine-mp (Packagist) ECOSYSTEM:introduced=0,fixed=3.26.5.

**Is there a fix for CVE-2022-51018?** Yes. pocketmine/pocketmine-mp (Packagist): upgrade to 3.26.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2022-51018 attacked?** It is attacked over the network.

**Am I affected by CVE-2022-51018?** Check whether you run pocketmine/pocketmine-mp (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- pocketmine/pocketmine-mp (Packagist): upgrade to 3.26.5 or later

  ```sh
  composer require pocketmine/pocketmine-mp:^3.26.5
  ```


## Technical details

The vulnerability is an input validation failure in book page handling. PocketMine-MP does not enforce limits on individual page text length, total page count, or author/title length. An authenticated player with a writable book can create oversized NBT objects that exceed protocol or storage limits: in PM3, chunks exceed the 1 MB size limit; in PM4, individual TAG_String values exceed 32 KiB. Attack requires network access and a valid game account with book access. Patches are available in versions 3.26.5 and 4.0.5.

## Affected products

- PocketMine PocketMine-MP 3.26.4 and earlier, 4.0.0–4.0.4

## Identifiers

- CVE-2022-51018
- GHSA-p62j-hrxm-xcxf

## Timeline

- 2022-01-04: disclosed: GitHub security advisory GHSA-p62j-hrxm-xcxf published
- 2022: patched: Fixed in versions 3.26.5 and 4.0.5

## References

- [https://github.com/pmmp/PocketMine-MP/security/advisories/GHSA-p62j-hrxm-xcxf](https://github.com/pmmp/PocketMine-MP/security/advisories/GHSA-p62j-hrxm-xcxf)
- [https://www.vulncheck.com/advisories/pocketmine-mp-before-3.26.5-input-validation-via-book-pages](https://www.vulncheck.com/advisories/pocketmine-mp-before-3.26.5-input-validation-via-book-pages)

## Related threats

- [PocketMine-MP denial of service in ModalFormResponsePacket handling](https://junglewise.ai/threats/cve-2026-86204-pocketmine-mp-denial-of-service-in-modalformresponsepacket)
- [PocketMine-MP item duplication via despawn entity attack race condition](https://junglewise.ai/threats/cve-2026-86203-pocketmine-mp-item-duplication-via-despawn-entity-attack-race)
- [PocketMine-MP network amplification in ActorEventPacket](https://junglewise.ai/threats/cve-2026-86202-pocketmine-mp-network-amplification-in-actoreventpacket)
- [PocketMine-MP denial of service in LoginPacket processing](https://junglewise.ai/threats/cve-2026-86201-pocketmine-mp-denial-of-service-in-loginpacket-processing)
- [PocketMine-MP denial of service in LoginPacket handler](https://junglewise.ai/threats/cve-2026-86200-pocketmine-mp-denial-of-service-in-loginpacket-handler)