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High

Uncapped length of skin data fields submitted by players

  • Disclosed: 06.01.2022
  • Updated: 11.10.2026 10:22

Impact

Some skin data fields (e.g. skinID, geometryName) are not capped in length. These fields are typically saved in the NBT data of a player when the player quits the server, or during an autosave.

This is problematic due to the 32767 byte limit on TAG_Strings. If any of these fields exceeds 32767 bytes, an exception will be thrown during data saving, which will cause the server to crash.

Other fields (such as skinGeometryData) are also uncapped, but those have a much larger 2 GB length limit, so this is not a concern for those, particularly considering the decompressed packet size limit of 2 MB.

Patches

PM3: 958a9dbf0fe3131ab60319c5a939f5dfbfe5dfbb PM4: 6492cac5c10f9fa8443ceddd2191a7b65b73f601

Workarounds

A plugin may check player skins during PlayerLoginEvent and PlayerSkinChangeEvent and ensure that the offending fields are not larger than 32767 bytes.

For more information

If you have any questions or comments about this advisory:

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Composer package pocketmine/pocketmine-mp < 3.26.5, >= 4.0.0, < 4.0.5 3.26.5, 4.0.5

References

CVSS score 7.5/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE)
-
Platform
Composer
Package
pocketmine/pocketmine-mp
Disclosed
06.01.2022
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-c6fg-99pr-25m9 - CC BY 4.0

Vulnerability history: pocketmine/pocketmine-mp

All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (30) in the archive
Total entries
30
First → latest
11.2020 04.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 20
  • Medium 8
  • Low 2

Disclosures per year

Severity:
  1. PocketMine-MP: JSON decoding of unlimited size large arrays/objects in ModalFormResponse Handling
    High CVE-2026-86204 < 5.39.2 5.39.2
  2. PocketMine-MP: LogDoS by large complex unknown property logging in clientData in LoginPacket
    High · 7.5 CVE-2026-86201 < 5.41.1 5.41.1
  3. PocketMine-MP `ResourcePackDataInfoPacket` amplification vulnerability due to lack of resource pack sequence status checking
    High CVE-2025-71417 < 5.32.1 5.32.1
  4. PocketMine-MP server crash with certain invalid JSON payloads in `LoginPacket` due to dependency vulnerability (3rd time)
    High · 7.5 CVE-2024-58381 < 5.11.1 5.11.1
  5. PocketMine-MP BookEditPacket crash when inventory slot in the packet is invalid
    High · 7.5 CVE-2024-58380 < 5.11.2 5.11.2
  6. PocketMine-MP server crash with certain invalid JSON payloads in `LoginPacket` due to dependency vulnerability (again)
    High · 7.5 CVE-2023-54390 >= 5.0.0, < 5.3.1, < 4.23.1 5.3.1, 4.23.1
  7. PocketMine-MP server crash due to incorrect EC curve used for LoginPacket identityPublicKey
    High · 7.5 CVE-2023-54355 >= 5.2.0, < 5.3.1 5.3.1
  8. PocketMine-MP vulnerable to server crash using badly formatted sign NBT in BlockActorDataPacket
    High · 7.5 CVE-2023-54392 >= 4.20.0, < 4.22.3, >= 5.0.0, < 5.2.1 4.22.3, 5.2.1
  9. PocketMine-MP vulnerable to improperly checked dropped item count leading to server crash
    High · 7.5 CVE-2023-7332 < 4.18.1 4.18.1
  10. PocketMine-MP vulnerable to server crash with certain invalid JSON payloads in `LoginPacket` due to vulnerable dependency
    High · 7.5 CVE-2023-54393 < 4.20.5, >= 4.21.0, < 4.21.1 4.20.5, 4.21.1
  11. PocketMine-MP has improperly handled dye colour IDs in banner NBT, leading to server crash
    High · 7.5 CVE-2023-54396 < 4.8.1 4.8.1
  12. PocketMine-MP invalid skin geometry JSON data leading to server crash
    High · 7.5 CVE-2022-51009 < 4.7.2 4.7.2
  13. Improperly checked IDs on itemstacks received from the client leading to server crash in PocketMine-MP
    High · 7.5 CVE-2022-51010 >= 4.0.0-BETA5, < 4.4.2 4.4.2
  14. Insufficient type validation in pocketmine/pocketmine-mp
    High · 7.5 CVE-2022-51012 < 4.2.9 4.2.9
  15. Improperly checked metadata on tools/armour itemstacks received from the client
    High · 7.5 CVE-2022-51013 < 4.2.4 4.2.4
  16. NaN/INF in serverbound movement packets can crash clients and servers
    High · 7.5 CVE-2021-48007 < 3.18.1 3.18.1
  17. Unhandled exception when decoding form response JSON
    High · 7.5 CVE-2022-51014 >= 4.0.0, < 4.0.7 4.0.7
  18. Unchecked validity of Facing values in PlayerActionPacket
    High · 7.5 CVE-2022-51015 < 4.0.6 4.0.6
  19. Uncapped length of skin data fields submitted by players this entry
    High · 7.5 CVE-2022-51017 < 3.26.5, >= 4.0.0, < 4.0.5 3.26.5, 4.0.5
  20. Exploitable inventory component chaining in PocketMine-MP
    High CVE-2020-37277 < 3.15.4 3.15.4

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