GHSA-P62J-HRXM-XCXF

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

Workarounds

Ban writable books, or use a plugin to cancel PlayerEditBookEvent to cancel the event if strlen(text) > 1024 || mb_strlen(text) > 256.

For more information

If you have any questions or comments about this advisory:

• Email us at [email protected]

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 TAG_String 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.

GHSA-P62J-HRXM-XCXF has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.26.5, 4.0.5); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

The bug has been fixed in 3.26.5 and 4.0.5.

1. What is GHSA-P62J-HRXM-XCXF? GHSA-P62J-HRXM-XCXF is a medium-severity security vulnerability in pocketmine/pocketmine-mp (composer), affecting versions < 3.26.5. It is fixed in 3.26.5, 4.0.5.
2. How severe is GHSA-P62J-HRXM-XCXF? GHSA-P62J-HRXM-XCXF has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of pocketmine/pocketmine-mp are affected by GHSA-P62J-HRXM-XCXF? pocketmine/pocketmine-mp (composer) versions < 3.26.5 is affected.
4. Is there a fix for GHSA-P62J-HRXM-XCXF? Yes. GHSA-P62J-HRXM-XCXF is fixed in 3.26.5, 4.0.5. Upgrade to this version or later.
5. Is GHSA-P62J-HRXM-XCXF exploitable, and should I be worried? Whether GHSA-P62J-HRXM-XCXF is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-P62J-HRXM-XCXF is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-P62J-HRXM-XCXF?
   • Upgrade pocketmine/pocketmine-mp to 3.26.5 or later
   • Upgrade pocketmine/pocketmine-mp to 4.0.5 or later

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