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Medium

Denial-of-service vulnerability processing large chat messages containing many newlines

  • Disclosed: 25.05.2022
  • Updated: 11.10.2026 10:22

Impact

PocketMine-MP caps maximum chat message length at 512 Unicode characters, or about 2048 bytes. No more than 2 chat messages may be sent per tick. However, due to legacy reasons, incoming chat message blobs are split by \n, and each part is treated as a separate message, the length of each part is individually checked. The length of the whole message is not checked.

This leads to an exploitable performance issue, in which a malicious client may send a chat packet of several megabytes containing nothing but \n newline characters. The server will parse this into a very large array and spend a long time (several milliseconds) iterating over it for no reason.

Furthermore, due to the lack of sufficient rate limit checks before parsing messages, malicious clients may bombard the server with many thousands of these malicious messages, causing lockups for a significant amount of time (seconds or minutes).

Patches

This bug was addressed in https://github.com/pmmp/PocketMine-MP/commit/df33e179e5d3ff13b56a2d7060bf592b0f797258 by:

  • checking the length of the incoming message as a whole before parsing it - it may not be larger than messageCounter * maxChatMessageSize (messageCounter is decremented once for every message sent)
  • limiting the maximum number of times a message may be split on newlines before giving up and discarding the message (maximum 3 parts; anything after the first 2 parts is discarded)

Workarounds

Handle DataPacketReceiveEvent and check for these excessive newlines in incoming TextPacket.

For more information

If you have any questions or comments about this advisory:

Affected software

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PlatformPackageVulnerable versionsFixed in
Composer package pocketmine/pocketmine-mp < 4.2.10 4.2.10

References

CVSS score 5.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness (CWE)
-
Platform
Composer
Package
pocketmine/pocketmine-mp
Disclosed
25.05.2022
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-gj94-v4p9-w672 - 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. Denial-of-service vulnerability processing large chat messages containing many newlines this entry
    Medium · 5.3 CVE-2022-51011 < 4.2.10 4.2.10
  15. Insufficient type validation in pocketmine/pocketmine-mp
    High · 7.5 CVE-2022-51012 < 4.2.9 4.2.9
  16. Improperly checked metadata on tools/armour itemstacks received from the client
    High · 7.5 CVE-2022-51013 < 4.2.4 4.2.4
  17. NaN/INF in serverbound movement packets can crash clients and servers
    High · 7.5 CVE-2021-48007 < 3.18.1 3.18.1
  18. Unhandled exception when decoding form response JSON
    High · 7.5 CVE-2022-51014 >= 4.0.0, < 4.0.7 4.0.7
  19. Unchecked validity of Facing values in PlayerActionPacket
    High · 7.5 CVE-2022-51015 < 4.0.6 4.0.6
  20. Uncapped length of skin data fields submitted by players
    High · 7.5 CVE-2022-51017 < 3.26.5, >= 4.0.0, < 4.0.5 3.26.5, 4.0.5
  21. Exploitable inventory component chaining in PocketMine-MP
    High CVE-2020-37277 < 3.15.4 3.15.4

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