CVE-2025-71418 in PocketMine-MP
Summary
by MITRE • 09/09/2026
PocketMine-MP versions before 5.25.2 fail to limit the explode() function in packet parsing, allowing malicious clients to waste server resources. Attackers can send crafted packets with excessive delimiters to consume CPU and memory through sign editing, JWT parsing, and command parsing endpoints.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified in PocketMine-MP versions prior to 5.25.2 represents a significant resource exhaustion flaw rooted in the improper validation of input data during packet processing. Specifically, the application fails to enforce appropriate limits on the explode() function when handling incoming network packets from clients. In many server-side applications, particularly those written in PHP like PocketMine-MP, the explode() function is commonly used to split strings into arrays based on a specified delimiter. However, without strict constraints on input length or complexity, this operation can become computationally expensive and memory-intensive if provided with maliciously crafted inputs containing excessive delimiters. This lack of sanitization allows attackers to exploit the server's processing logic by sending packets that trigger disproportionate resource consumption relative to their size.
The operational impact of this vulnerability is severe for Minecraft servers running affected versions, as it directly facilitates Denial of Service attacks through CPU and memory exhaustion. Attackers can leverage multiple endpoints within the game protocol to execute these exploits effectively. One primary vector involves sign editing functionality, where a malicious client sends packets with an unusually high number of delimiter characters in the text fields intended for signs placed by players. Another critical attack surface is found in JSON Web Token parsing mechanisms used for authentication or session management, where crafted tokens containing excessive delimiters can cause the parser to consume significant computational resources during validation. Additionally, command parsing endpoints are susceptible, as commands sent with malformed structures rich in delimiter characters force the server to perform extensive string splitting operations before determining if a valid command exists.
From a technical classification perspective, this vulnerability aligns closely with CWE-787: Out-of-bounds Write and CWE-400: Uncontrolled Resource Consumption. The core issue is not necessarily a buffer overflow in the traditional sense but rather an unbounded resource allocation triggered by specific input patterns that exceed expected operational parameters. In terms of offensive security frameworks, this behavior maps to MITRE ATT&CK technique T1498: Network Denial of Service, specifically under sub-techniques involving application layer exhaustion or protocol abuse. The attacker does not need to crash the server immediately but can degrade its performance significantly by forcing it to spend cycles on parsing invalid or excessively complex data structures rather than handling legitimate game logic.
Mitigation strategies must focus on implementing strict input validation and resource limits at the packet processing level. Developers should enforce maximum length constraints on all string fields received from clients, particularly those involved in sign text, command arguments, and authentication tokens. Furthermore, custom implementations of delimiter-based parsing functions should include safeguards such as limiting the number of resulting array elements or setting timeouts for long-running parse operations. Upgrading to version 5.25.2 or later is essential, as these versions address the underlying flaw by introducing proper limits on the explode() function usage within packet parsers. Administrators unable to upgrade immediately should consider deploying network-level rate limiting and deep packet inspection rules to detect and block packets with abnormally high delimiter counts before they reach the application layer.