Heap Out-of-Bounds Read in FFmpeg via V4L2 Buffer Handling

Executive Summary

FFmpeg through version 9.0.2 has a heap out-of-bounds read vulnerability in the v4l2_buffer_swframe_to_buf() function. This flaw occurs when frames with negative linesize values are processed, particularly in V4L2 M2M encoders. Attackers can exploit this by providing specially crafted bottom-up AVI or PNM/PFM files, causing crashes or leaking heap memory into encoded output.

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Detection Guidance

To detect this vulnerability, monitor FFmpeg processes for crashes when handling AVI or PNM/PFM files with negative linesize. Check logs for heap memory leaks in encoded output. Use static analysis tools to scan for vulnerable FFmpeg versions (9.0.2 or earlier).

• Check FFmpeg version: ffmpeg -version | grep n9.0.2
• Test with suspicious files: ffmpeg -i malicious.avi -vcodec libv4l2 output.mp4
• Monitor system logs for segmentation faults or memory errors during transcoding

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Impact Analysis

This vulnerability may allow attackers to crash applications using FFmpeg or leak sensitive memory contents. If exploited, it could lead to denial-of-service conditions or unauthorized data exposure in systems processing malicious media files.

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Compliance Impact

This vulnerability may lead to heap memory leaks during video encoding, which could expose sensitive data in encoded output. For GDPR, this could violate data protection principles if personal data is leaked. For HIPAA, it might compromise protected health information if medical video data is involved.

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Mitigation Strategies

Upgrade FFmpeg to a patched version (commit b8f159858e2fd29dae4fa34d9e713bbf9bbf190e or later). Avoid transcoding untrusted AVI or PNM/PFM files with V4L2 M2M encoders. Implement input validation for media files.

• Apply the patch from commit b8f159858e2fd29dae4fa34d9e713bbf9bbf190e
• Disable V4L2 M2M encoding for untrusted files until patched
• Monitor for crashes or memory leaks in FFmpeg processes

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