CVE-2011-0531 in VLC Media Player
Summary
by MITRE
demux/mkv/mkv.hpp in the MKV demuxer plugin in VideoLAN VLC media player 1.1.6.1 and earlier allows remote attackers to cause a denial of service (crash) and execute arbitrary commands via a crafted MKV (WebM or Matroska) file that triggers memory corruption, related to "class mismatching" and the MKV_IS_ID macro.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 05/11/2025
The vulnerability identified as CVE-2011-0531 represents a critical memory corruption issue within the MKV demuxer plugin of VideoLAN VLC media player versions 1.1.6.1 and earlier. This flaw exists in the demux/mkv/mkv.hpp file and specifically targets the handling of MKV, WebM, and Matroska format files. The vulnerability arises from improper handling of class mismatching scenarios combined with flawed implementation of the MKV_IS_ID macro, creating a condition where maliciously crafted media files can trigger unpredictable behavior in the application's memory management system.
The technical exploitation of this vulnerability occurs when a remote attacker crafts a specially designed MKV file that contains malformed data structures. The MKV_IS_ID macro, which is intended to validate identifier fields within the Matroska container format, fails to properly handle certain edge cases that result in memory corruption. When VLC processes such a crafted file, the demuxer plugin attempts to parse the malformed data using the flawed macro, leading to buffer overflows or other memory corruption conditions that can cause the application to crash or potentially execute arbitrary code. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read errors that can lead to memory corruption.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially enable remote code execution on systems running vulnerable versions of VLC. Attackers can leverage this weakness by distributing malicious MKV files through various vectors such as email attachments, malicious websites, or peer-to-peer networks. When victims open these files with vulnerable VLC versions, the application crashes or may even execute attacker-controlled code with the privileges of the user running VLC. This makes the vulnerability particularly dangerous in enterprise environments where media players are commonly used and where users may inadvertently encounter malicious content. The vulnerability aligns with ATT&CK technique T1203, which describes exploiting software vulnerabilities for remote code execution, and T1068, which covers exploiting local privilege escalation opportunities through application flaws.
Organizations and users should immediately update to VLC versions 1.1.7 or later, where this vulnerability has been patched through improved validation of identifier fields and enhanced memory management within the MKV demuxer plugin. System administrators should implement network-level controls to block access to known malicious media files and consider deploying application whitelisting solutions to restrict execution of untrusted media files. Additionally, regular security updates and patch management processes should be enforced across all systems that may encounter media files, particularly in environments where users have broad internet access or receive external email attachments. The vulnerability demonstrates the critical importance of proper input validation in multimedia processing libraries and highlights the need for robust memory safety practices in media player implementations.