critical severityConfidence highHistorical record

Rails Active Storage: a crafted upload can write and read files on the server through ImageMagick and FFmpeg (GHSA-f3w6-w445-fwh9, GHSA-v924-7rp8-4mxh)

Direct answer

Rails Active Storage: a crafted upload can write and read files on the server through ImageMagick and FFmpeg (GHSA-f3w6-w445-fwh9, GHSA-v924-7rp8-4mxh), also tracked as GHSA-f3w6-w445-fwh9 / GHSA-v924-7rp8-4mxh / Rails Active Storage ImageMagick file write is a critical-severity threat campaign HOL Guard tracked from Nov 4, 2026 to Nov 4, 2026, verified against 5 primary sources and last reviewed Nov 4, 2026. Active tracking has ended and the record remains published as a permanent historical research record.

On 2026-11-04 (UTC) Rails released 8.0.5.2 and 8.1.4.1, fixing 21 security issues. GHSA-f3w6-w445-fwh9 (Critical, CVSS 9.8): Active Storage ran ImageMagick analysis on attach with no coder restrictions, so an unauthenticated attacker who can upload a crafted file may write arbitrary files on the server and, with the Disk service, read files readable by the app process such as secret_key_base. It affects apps using variant_processor :mini_magick (default on load_defaults 6.1 or earlier) under an ImageMagick policy that does not deny the coders involved (Debian and Ubuntu policies do not). GHSA-v924-7rp8-4mxh (High, CVSS 8.8): Active Storage kept the uploaded extension on tempfiles passed to ffprobe, ffmpeg and ImageMagick, letting the uploader pick the decoder; an FFmpeg built with AviSynth evaluates .avs files as scripts, which could disclose files through a preview image or load an uploaded native library. Both affect activestorage < 8.0.5.2 and >= 8.1, < 8.1.4.1. No CVE IDs, not on CISA KEV, and no known exploitation at publication.

Also tracked as GHSA-f3w6-w445-fwh9 · GHSA-v924-7rp8-4mxh · Rails Active Storage ImageMagick file write · Rails 8.1.4.1 security release · Rails 8.0.5.2 security release · activestorage arbitrary file read

First observed
Nov 4, 2026
Last observed
Nov 4, 2026
Last reviewed
Nov 4, 2026
Tracking ended
Nov 4, 2026

Record exports

JSON recordArtifact CSVSTIX 2.1 bundle

Uncertainty and limitations

Read the evidence limits before acting on this record.

Rails says one ImageMagick attack chain was reported and does not assume it is the only one. No CVE IDs had been assigned at publication. Exposure depends on per-app configuration (variant processor, analyzers, storage service, host ImageMagick policy and FFmpeg build), which HOL cannot see.

  • Apps that never accept uploads from untrusted users are not affected by either advisory.
  • The critical ImageMagick issue does not apply to apps using :vips (the default for load_defaults 7.0 and later) unless they process images with ImageMagick.
  • The file read half of GHSA-f3w6-w445-fwh9 requires attachments stored with the Disk service; cloud storage narrows it to file write.
  • The AviSynth code execution path in GHSA-v924-7rp8-4mxh needs an FFmpeg built with --enable-avisynth plus the AviSynthPlus runtime; upstream, common distribution and Homebrew FFmpeg builds do not enable it.
  • Hosts whose ImageMagick policy already denies MSL, the Ghostscript coders and the gs delegate are not exposed to the reported coder chain.

Guard coverage and policy

What Guard's reviewed assertions do and do not claim for this campaign, and the reviewed starting points for defense.

Not covered, or partially covered

  • not covered

    HOL Guard reviews AI coding agent actions before they run. It does not patch Rails apps or filter uploads; the fix is upgrading activestorage and rotating exposed secrets.

No campaign-specific policy guidance is published.

Safe next step. Campaign guidance is defensive context. It does not auto-apply policy or claim universal campaign coverage.

Open policy controlsCampaign-specific emergency policy starting point

Timeline

Reviewed events, oldest first, each tied to a verified source.

  1. Vendor action

    Rails 8.0.5.2 released with Active Storage security fixes.

    Source:Rails Versions 8.0.5.2 and 8.1.4.1 have been released

  2. Vendor action

    Rails 8.1.4.1 released with Active Storage security fixes.

    Source:Rails Versions 8.0.5.2 and 8.1.4.1 have been released

  3. Disclosure

    Rails publishes GHSA-v924-7rp8-4mxh (High, CVSS 8.8), arbitrary file read and possible code execution in Active Storage video previews, analysis and image processing.

    Source:GHSA-v924-7rp8-4mxh: Possible arbitrary file read and remote code execution in Active Storage video previews, analysis and image processing

  4. Disclosure

    Rails publishes GHSA-f3w6-w445-fwh9 (Critical, CVSS 9.8), arbitrary file write and read in Active Storage image analysis.

    Source:GHSA-f3w6-w445-fwh9: Possible arbitrary file write and read in Active Storage image analysis

  5. Update

    HOL Guard publishes an operator write-up with config checks, the mini_magick 5.1 boot trap, secret rotation guidance and Rails 7.2 workarounds.

    Source:HOL: A crafted photo upload can read and write files on Rails servers

Publication clock: 0.5 hours from reviewed disclosure timestamp to HOL publication; 12-hour critical target; within target.

Reviewed artifacts

The specific artifacts this record concerns, as reviewed. Names and versions are shown as text; a registry link is not recorded here.

  • activestorage@< 8.0.5.2, >= 8.1.0 < 8.1.4.1rubygemspackage
  • mini_magick@< 5.1 (incompatible with the fix when variant_processor is :mini_magick)rubygemspackage

Sources

Every claim on this record is traceable to the sources below.

Campaign questions, answered

On 2026-11-04 (UTC) Rails released 2 and HOL Guard tracked the campaign from Nov 4, 2026 to Nov 4, 2026.

No. Active tracking ended Nov 4, 2026; this page remains as a labeled historical research record and does not imply the threat is currently active.

The record cites 5 primary sources, names 2 reviewed artifacts, and was last fully reviewed Nov 4, 2026 by HOL Guard Security Publishing. Its uncertainty and limitations are stated on the record itself.

Campaign guidance is defensive context. It does not auto-apply policy or claim universal campaign coverage.

The permalink above is permanent. The full record can be downloaded from this page as JSON, an artifact CSV, and a STIX 2.1 bundle, and corrections can be requested through the published correction path on the record. Rails says one ImageMagick attack chain was reported and does not assume it is the only one. No CVE IDs had been assigned at publication.

Reviewed in full by HOL Guard Security Publishing.

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Record HGTC-2026-0372EC42