Active Storage makes it simple to upload and reference files in cloud services and attach those files to Active Record objects. Prior to 8.0.5.2 and from 8.1 until 8.1.4.1, Active Storage's ActiveStorage::Previewer::VideoPreviewer, ActiveStorage::Analyzer::VideoAnalyzer, and ActiveStorage::Analyzer::AudioAnalyzer pass uploaded blob contents to FFmpeg without restricting the demuxer. A direct upload can retain a client-declared video/* or audio/* content type for an HLS playlist. FFmpeg content probing selects the hls demuxer, which opens attacker-named file:// segments when the blob is previewed or analyzed. Applications that accept untrusted uploads and generate video previews or analyze video or audio attachments can disclose a local media file readable by the application process when the attacker knows its path. This issue is fixed in versions 8.0.5.2 and 8.1.4.1.

Affected: RubyGems: activestorage

### Impact 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.

### Details 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.

### Workarounds 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`.

### Releases The fixed release…

Affected: Ubuntu:Pro:16.04:LTS: rails, Ubuntu:Pro:18.04:LTS: rails, Ubuntu:Pro:20.04:LTS: rails, Ubuntu:Pro:22.04:LTS: rails, Ubuntu:24.04:LTS: rails, Ubuntu:26.10: rails, Ubuntu:26.04:LTS: rails

Active Storage makes it simple to upload and reference files in cloud services and attach those files to Active Record objects. Prior to 8.0.5.2 and from 8.1 until 8.1.4.1, Active Storage's ActiveStorage::Previewer::VideoPreviewer, ActiveStorage::Analyzer::VideoAnalyzer, and ActiveStorage::Analyzer::AudioAnalyzer pass uploaded blob contents to FFmpeg without restricting the demuxer. A direct upload can retain a client-declared video/* or audio/* content type for an HLS playlist. FFmpeg content probing selects the hls demuxer, which opens attacker-named file:// segments when the blob is previewed or analyzed. Applications that accept untrusted uploads and generate video previews or analyze video or audio attachments can disclose a local media file readable by the application process when the attacker knows its path. This issue is fixed in versions 8.0.5.2 and 8.1.4.1.

Ein Angreifer kann mehrere Schwachstellen in Ruby on Rails ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Daten zu manipulieren, um falsche Informationen darzustellen, um einen Cross-Site Scripting Angriff durchzuführen und um Sicherheitsvorkehrungen zu umgehen.