CVE-2022-48434 in FFmpeg
Summary
by MITRE • 03/29/2023
libavcodec/pthread_frame.c in FFmpeg before 5.1.2, as used in VLC and other products, leaves stale hwaccel state in worker threads, which allows attackers to trigger a use-after-free and execute arbitrary code in some circumstances (e.g., hardware re-initialization upon a mid-video SPS change when Direct3D11 is used).
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Analysis
by VulDB Data Team • 04/27/2025
The vulnerability CVE-2022-48434 represents a critical use-after-free condition within FFmpeg's hardware acceleration handling mechanism, specifically in the libavcodec/pthread_frame.c component. This flaw exists in FFmpeg versions prior to 5.1.2 and affects numerous applications including VLC media player and other multimedia frameworks that rely on FFmpeg for video decoding operations. The vulnerability stems from improper cleanup of hardware acceleration state within worker threads, creating a persistent security risk that can be exploited by malicious actors to execute arbitrary code on affected systems. The issue manifests particularly when hardware acceleration is utilized, making it especially dangerous in multimedia environments where hardware decoding is commonly employed for performance optimization.
The technical root cause of this vulnerability lies in the improper management of hardware acceleration contexts within multithreaded video decoding operations. When FFmpeg processes video streams with hardware acceleration enabled, particularly through Direct3D11 on Windows platforms, worker threads maintain state information about hardware resources. During normal operation, when a video stream undergoes changes such as a mid-video SPS (Sequence Parameter Set) update, the system should properly clean up and reinitialize hardware acceleration resources. However, the flaw prevents complete cleanup of stale hardware acceleration state, leaving dangling references to freed memory regions. This stale state can persist across multiple video processing operations, creating conditions where subsequent memory operations may access deallocated memory, resulting in the use-after-free vulnerability that attackers can leverage for code execution.
The operational impact of CVE-2022-48434 extends beyond simple code execution capabilities to encompass significant security implications for multimedia applications and systems. Attackers can exploit this vulnerability by crafting specially crafted video content that triggers the specific conditions leading to stale hardware state retention. When such content is processed through affected applications like VLC, the use-after-free condition can be triggered during hardware re-initialization processes, potentially allowing remote code execution with the privileges of the affected application. This vulnerability is particularly concerning in environments where users frequently process untrusted multimedia content, as it can be exploited through simple media playback scenarios without requiring special privileges or complex attack vectors. The vulnerability's impact is further amplified by the widespread adoption of FFmpeg across numerous multimedia applications and operating systems, making it a significant threat to end-user security.
Mitigation strategies for CVE-2022-48434 primarily focus on updating to patched versions of FFmpeg, specifically version 5.1.2 or later, which contain the necessary fixes for proper hardware acceleration state cleanup. System administrators and security professionals should prioritize updating all affected applications that rely on FFmpeg, including VLC media player, various streaming platforms, and multimedia frameworks. Additionally, implementing runtime protections such as address space layout randomization and stack canaries can provide additional defense-in-depth measures against exploitation attempts. Organizations should also consider implementing content filtering mechanisms to prevent processing of untrusted multimedia content, particularly when hardware acceleration is enabled. From a compliance perspective, this vulnerability aligns with CWE-416, which describes use-after-free conditions, and can be mapped to ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation may involve executing malicious code within the application context. The vulnerability demonstrates the importance of proper resource management in multithreaded environments and highlights the need for comprehensive testing of hardware acceleration features in multimedia processing frameworks.