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A GitHub-reviewed security advisory, not necessarily under active exploitation the way our CISA KEV advisories are, but a real, disclosed vulnerability in an open-source dependency.
Affected packages
Vulnerable: >= 8.1.0.beta1, < 8.1.4.1
Patched in 8.1.4.1
Vulnerable: < 8.0.5.2
Patched in 8.0.5.2
Details
Active Storage's VideoPreviewer, VideoAnalyzer and AudioAnalyzer run ffmpeg and ffprobe on a blob's contents without restricting the input format, so FFmpeg selects a demuxer by probing the file. A blob created through a direct upload keeps the content type the client declared, so a client can store an HLS playlist under a video/* or audio/* type. When that blob is previewed or analyzed, the hls demuxer opens the file:// segments that the playlist names, and the preview image or the stored metadata could disclose a local media file that the application process can read and whose path the attacker knows.
Applications that accept uploads from untrusted users and generate video previews, or analyze video or audio attachments with FFmpeg, are affected.
The fixed releases limit the formats FFmpeg may open to common audio and video containers, configured by the new config.active_storage.ffmpeg_allowed_formats setting. Files in other formats no longer preview or receive media metadata; the Active Storage CHANGELOG names some of them and shows how to add a format to the list.
Applications that cannot upgrade can stop Active Storage from running FFmpeg on uploaded files by removing ActiveStorage::Previewer::VideoPreviewer from config.active_storage.previewers, and ActiveStorage::Analyzer::VideoAnalyzer and ActiveStorage::Analyzer::AudioAnalyzer from config.active_storage.analyzers.
The fixed releases are available at the normal locations.
Patches for those who cannot upgrade at once:
This issue was responsibly reported by HackerOne researcher w3rmut.
EPSS, exploit probability
Low0.28%
estimated chance of real-world exploitation in the next 30 days, higher than 20.6% of every CVE FIRST.org scores
Refreshed 11/13/2026, via FIRST.org's EPSS model, not CVSS, this measures likelihood of exploitation, not how severe it would be.
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