CVE-2016-1898 in FFmpeg
Summary
by MITRE
FFmpeg 2.x allows remote attackers to conduct cross-origin attacks and read arbitrary files by using the subfile protocol in an HTTP Live Streaming (HLS) M3U8 file, leading to an external HTTP request in which the URL string contains an arbitrary line of a local file.
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Analysis
by VulDB Data Team • 01/27/2025
The vulnerability identified as CVE-2016-1898 represents a critical security flaw in FFmpeg version 2.x that enables remote attackers to perform cross-origin attacks and unauthorized file access through the manipulation of HTTP Live Streaming (HLS) M3U8 files. This vulnerability specifically exploits the subfile protocol implementation within FFmpeg's media processing framework, creating a pathway for attackers to bypass normal file access restrictions and potentially exfiltrate sensitive local data. The flaw operates by leveraging the subfile protocol's handling of HTTP requests within HLS playlists, where maliciously crafted M3U8 files can contain URLs that reference local file system paths, allowing the application to read arbitrary files on the server hosting the media processing component.
The technical execution of this vulnerability involves the manipulation of the subfile protocol within FFmpeg's HLS parsing mechanism, which permits the inclusion of local file references within HTTP requests that are processed by the media player. When FFmpeg processes an M3U8 file containing a subfile protocol URL, it performs an external HTTP request that includes a string representing a local file path, effectively enabling attackers to read content from the local filesystem. This behavior violates fundamental security principles of file access control and demonstrates a lack of proper input validation and sanitization within the protocol handling components. The vulnerability specifically affects versions of FFmpeg prior to 3.0, where the subfile protocol implementation did not adequately restrict access to local resources, making it susceptible to malicious exploitation through carefully crafted media playlists.
The operational impact of CVE-2016-1898 extends beyond simple information disclosure, as it creates a persistent attack vector that can be exploited across various systems utilizing FFmpeg for media processing. Attackers can leverage this vulnerability to access sensitive configuration files, user data, system logs, and other locally stored information that may contain credentials, personal data, or system architecture details. The cross-origin nature of the attack means that malicious actors can potentially exploit this vulnerability from remote locations without requiring physical access to the target system, making it particularly dangerous for web applications, content delivery networks, and media processing services. This vulnerability aligns with CWE-20, which addresses improper input validation, and represents a classic example of how protocol handling flaws can lead to unauthorized data access in multimedia processing applications.
Mitigation strategies for this vulnerability require immediate upgrade to FFmpeg version 3.0 or later, where the subfile protocol handling has been significantly enhanced to prevent local file access through HTTP requests. Organizations should also implement strict input validation for all HLS M3U8 files processed by FFmpeg, particularly when these files originate from untrusted sources. Network-level protections such as firewall rules and proxy configurations can help limit access to local resources, while application-level restrictions should prevent the processing of externally sourced media files without proper sanitization. The vulnerability demonstrates the importance of proper protocol isolation and input validation in multimedia frameworks, and aligns with ATT&CK technique T1059.007 for execution through scripting languages and T1566 for the use of malicious content to gain access to systems. Security teams should also implement monitoring for unusual HTTP requests and file access patterns that may indicate exploitation attempts, as the vulnerability can be used in conjunction with other attack vectors to create more sophisticated compromise scenarios.