CVE-2022-51014 in PocketMine-MP
Summary
by MITRE • 09/07/2026
PocketMine-MP before 4.0.7 contains an unhandled exception vulnerability in the ModalFormResponsePacket handler when processing malformed JSON from clients. Attackers can send specially crafted form response packets with invalid JSON to trigger an uncaught InvalidArgumentException, causing server crashes.
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Analysis
by VulDB Data Team • 09/07/2026
The PocketMine-MP software, a widely used PHP-based Minecraft: Bedrock Edition multiplayer server implementation, contains a critical input validation flaw within its ModalFormResponsePacket handler prior to version 4.0.7. This vulnerability stems from the application's failure to properly sanitize and validate JSON data received from client connections before processing it for internal state updates. When a remote attacker sends a specially crafted form response packet containing malformed or invalid JSON structures, the underlying PHP runtime encounters an InvalidArgumentException that is not caught by any error handling mechanism within the specific code path responsible for parsing these packets. This lack of exception management results in an unhandled crash condition rather than a graceful degradation or rejection of the malicious input.
From a technical perspective, this flaw represents a classic case of improper input validation leading to application instability. The ModalFormResponsePacket is designed to handle user interactions with graphical forms presented within the game interface, such as dropdown selections or text inputs. By exploiting the parser's inability to recover from syntax errors in JSON payloads, an attacker can force the server process into a fatal error state. This aligns closely with CWE-754, which categorizes improper check for unusual or exceptional conditions, and specifically relates to CWE-20 where insufficient input validation allows malformed data to propagate through system layers without adequate checks. The vulnerability is particularly dangerous because it does not require authentication in many default configurations, allowing unauthenticated remote actors to trigger the crash simply by connecting to the server and sending a single malicious packet.
The operational impact of this vulnerability is severe due to its direct effect on service availability. Since the exception causes an immediate termination or restart of the affected thread or process depending on the PHP configuration, repeated exploitation can lead to a sustained Denial of Service condition for all connected players. This disrupts gameplay and administrative functions, effectively rendering the server inaccessible until it is manually restarted or automatically recovered if such mechanisms are in place but not triggered by this specific error type. The simplicity of the attack vector means that automated scanning tools could easily identify vulnerable instances on public networks, leading to widespread disruption across communities relying on PocketMine-MP for stable multiplayer experiences.
To mitigate this risk, administrators must upgrade their server software to version 4.0.7 or later, where the developers have implemented proper exception handling and input validation routines within the ModalFormResponsePacket handler. This ensures that malformed JSON is detected early in the parsing process, allowing the system to log the error safely and disconnect the offending client without crashing the entire service. Additionally, deploying network-level security controls such as rate limiting or IP-based access restrictions can provide a secondary layer of defense by throttling connection attempts from suspicious sources. Monitoring server logs for repeated InvalidArgumentException errors related to JSON parsing can also aid in early detection of exploitation attempts before they cause significant downtime. This incident underscores the importance of robust error handling practices in network-facing applications, particularly those written in interpreted languages like PHP where exception management is critical for maintaining stability under adversarial conditions. The vulnerability maps to MITRE ATT&CK technique T1499, Endpoint Denial of Service, as it involves overwhelming or crashing a specific endpoint through malformed input rather than resource exhaustion via volume alone.