CVE-2004-1220 in Battlefield 1942
Summary
by MITRE
Battlefield 1942 1.6.19 and earlier, and Battlefield Vietnam 1.2 and earlier, allows a remote master server to cause a denial of service (client crash) via a server reply that contains a large numplayers value, which triggers a null dereference.
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Analysis
by VulDB Data Team • 07/10/2025
The vulnerability identified as CVE-2004-1220 affects popular first-person shooter games Battlefield 1942 version 1.6.19 and earlier, as well as Battlefield Vietnam version 1.2 and earlier. This issue represents a classic denial of service vulnerability that exploits the client-side parsing of server responses within the game's master server communication protocol. The flaw manifests when a malicious or compromised master server responds to client queries with a crafted reply containing an excessively large numplayers value that exceeds the expected parameter boundaries.
The technical implementation of this vulnerability stems from inadequate input validation and boundary checking within the client software's response parsing mechanism. When the game client receives a server reply containing an oversized numplayers field, the application fails to properly validate the incoming data before processing it. This leads to a null dereference condition where the client attempts to access a null pointer or invalid memory location, causing the application to crash and terminate unexpectedly. The vulnerability specifically targets the client-side code that handles master server responses and processes player count information during network communication.
From an operational perspective, this vulnerability presents a significant risk to game availability and player experience within the Battlefield gaming ecosystem. Attackers can exploit this weakness by controlling or compromising a master server and sending malicious responses to clients, effectively causing widespread service disruption. The impact extends beyond individual client crashes to potentially affect entire gaming sessions and server availability, as players may be unable to connect to game servers or maintain stable connections. This vulnerability particularly affects multiplayer gaming environments where master server functionality is critical for client-server discovery and connection establishment.
The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions that can lead to null pointer dereferences and application crashes. From an ATT&CK framework perspective, this represents a denial of service attack vector that operates at the application layer, specifically targeting the game client's network communication stack. The exploit requires minimal privileges and can be executed remotely, making it particularly dangerous in multiplayer gaming environments where clients frequently connect to master servers for game discovery and matchmaking.
Mitigation strategies for this vulnerability include implementing proper input validation and boundary checking within client software, particularly for fields that contain numerical data such as player counts. Game developers should enforce maximum value limits for numplayers fields and implement defensive programming practices that prevent null pointer dereferences. Additionally, network administrators should consider implementing master server authentication mechanisms to verify the legitimacy of server responses, and clients should be updated to versions that include proper input sanitization and error handling. The most effective long-term solution involves patching the affected software versions to include robust validation of all incoming server data before processing, ensuring that any malformed responses are properly handled without causing application crashes.