CVE-2026-126188: Active Storage: Possible local file disclosure in video previews and analysis
CVE-2026-126188 · Severity: low · CVSS 3.7 · Published 2026-11-11
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.
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
Am I affected by CVE-2026-126188?
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