Executive brief
PocketMine-MP is a PHP-based server software for Minecraft: Bedrock Edition. During player login, a malicious client can send multiple duplicate resource pack completion packets to cause the server to create duplicate player objects, consuming excessive memory and bandwidth. This can degrade server performance and availability.
Technical details
The vulnerability is an improper validation issue in the ResourcePackClientResponsePacket STATUS_COMPLETED handler within the ResourcePacksPacketHandler class. When a client sends multiple ResourcePackClientResponsePacket packets with STATUS_COMPLETED status during the resource pack handshake phase, the handler fails to prevent repeated pre-spawn progression, allowing duplicate Player objects to be created from a single session. Attack vector is network-based with low attack complexity and low privileges required. An attacker can send batches of these packets to amplify memory consumption and outbound network traffic through duplication of large pre-spawn packets. The fix, released in version 5.44.2 (commit 7a27894), adds a check to prevent re-execution by clearing the handler after completion.
Affected products
- PocketMine PocketMine-MP before 5.44.2
Timeline
- 2026-06-24: disclosed
- 2026-09-09: patched: version 5.44.2 released