CVE-2018-9240 in ncmpc
Summary
by MITRE • 01/25/2023
ncmpc through 0.29 is prone to a NULL pointer dereference flaw. If a user uses the chat screen and another client sends a long chat message, a crash and denial of service could occur.
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Analysis
by VulDB Data Team • 02/26/2023
The vulnerability identified as CVE-2018-9240 affects ncmpc version 0.29 and earlier, representing a critical null pointer dereference flaw within the music player client's chat functionality. This issue manifests when users engage with the chat screen feature and encounter incoming chat messages exceeding normal length parameters from other connected clients. The flaw stems from inadequate input validation and memory management within the chat message processing pipeline, specifically failing to properly handle edge cases where message length exceeds expected boundaries. The vulnerability operates at the application layer, targeting the client-side execution environment of ncmpc, which is a command-line interface for controlling MPD music servers. This type of vulnerability falls under CWE-476, which categorizes null pointer dereference conditions as a common weakness in software security implementations.
The operational impact of this vulnerability extends beyond simple application instability to create potential denial of service scenarios that can disrupt user experience and system availability. When a malicious or malformed chat message is received, the ncmpc client attempts to dereference a null pointer during message processing, causing an immediate application crash. This crash occurs regardless of the user's current activity within the client, making it particularly disruptive in environments where continuous music playback and chat functionality are essential. The vulnerability can be exploited remotely through network communication with the MPD server, as chat messages are transmitted over the network protocol. Attackers can leverage this weakness to repeatedly send oversized chat messages, creating persistent denial of service conditions that prevent legitimate users from accessing the chat functionality or even using the music player itself.
The technical exploitation of CVE-2018-9240 requires minimal prerequisites, as it can be triggered through normal network communication with the affected MPD server. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1499.004, which involves network denial of service attacks through resource exhaustion or application crashes. The flaw represents a classic buffer overflow scenario in the chat message handling code, where the application fails to validate message boundaries before processing. This vulnerability impacts the integrity of the ncmpc client's execution environment and can potentially be chained with other weaknesses to create more sophisticated attack vectors. The issue highlights poor defensive programming practices and inadequate error handling within the application's message parsing routines. System administrators and users should be aware that this vulnerability affects not only individual client installations but also networked environments where multiple clients interact through a shared MPD server, making it a significant concern for collaborative music environments.
Mitigation strategies for CVE-2018-9240 include immediate patching of ncmpc to version 0.30 or later, where the null pointer dereference has been addressed through proper input validation and memory management. Users should also implement network-level filtering to restrict chat message sizes or disable chat functionality entirely if it is not essential to their workflow. Additional protective measures include monitoring network traffic for anomalous chat message patterns and implementing application-level rate limiting for chat communications. The vulnerability serves as a reminder of the importance of proper input validation and defensive programming practices in client applications. Organizations should conduct regular security assessments of their media player configurations and ensure that all components are running patched versions to prevent exploitation. The fix implemented in subsequent versions demonstrates proper error handling techniques that should be adopted across similar applications to prevent similar vulnerabilities from occurring in the future.