CVE-2009-4640 in FFmpeg
Summary
by MITRE
Array index error in vorbis_dec.c in FFmpeg 0.5 allows remote attackers to cause a denial of service and possibly execute arbitrary code via a crafted Vorbis file that triggers an out-of-bounds read.
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Analysis
by VulDB Data Team • 04/30/2026
The vulnerability identified as CVE-2009-4640 represents a critical array index error within the vorbis_dec.c component of FFmpeg version 0.5, constituting a security flaw that can be exploited by remote attackers to compromise system integrity. This issue manifests as an out-of-bounds read condition that occurs when processing specially crafted Vorbis audio files, which are commonly used in multimedia applications and streaming platforms. The flaw stems from inadequate bounds checking during the decoding process of Vorbis audio data, where the software fails to properly validate array indices before accessing memory locations, creating a pathway for malicious input to trigger unintended behavior.
The technical exploitation of this vulnerability involves the manipulation of Vorbis file headers and audio data structures to force the FFmpeg decoder into accessing memory beyond the allocated array boundaries. This out-of-bounds read can lead to unpredictable program behavior, including application crashes that result in denial of service conditions, or potentially more severe consequences if the attacker can manipulate the memory access patterns to execute arbitrary code within the context of the vulnerable application. The vulnerability is particularly concerning because Vorbis is a widely supported audio codec used across numerous multimedia applications, making the potential attack surface extensive.
From an operational impact perspective, this vulnerability affects any system running FFmpeg 0.5 or earlier versions that processes Vorbis audio content, including media servers, streaming platforms, and multimedia applications. The denial of service aspect can disrupt legitimate services by causing applications to crash when encountering maliciously crafted audio files, while the potential for arbitrary code execution presents a more severe threat that could allow attackers to gain unauthorized control over affected systems. The vulnerability's remote exploitation capability means that attackers do not need physical access to the target system and can potentially compromise systems through web-based media delivery or file sharing platforms.
Security professionals should note that this vulnerability aligns with CWE-129, which describes improper validation of array index values, and demonstrates characteristics consistent with ATT&CK technique T1203, involving the exploitation of software vulnerabilities for remote code execution. The flaw represents a classic buffer over-read condition that can be mitigated through proper bounds checking and input validation. Organizations should prioritize immediate patching of FFmpeg installations to version 0.6 or later, which includes fixes for this vulnerability. Additionally, implementing network-based intrusion detection systems to monitor for suspicious Vorbis file patterns and deploying application whitelisting policies can provide additional layers of defense against exploitation attempts. The vulnerability underscores the critical importance of maintaining up-to-date multimedia libraries and implementing comprehensive security testing procedures for all media processing components in enterprise environments.