CVE-2026-126082: Active Storage: Possible arbitrary file write and read in Active Storage image analysis
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-11 15:49 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
Active Storage makes it simple to upload and reference files in cloud services and attach those files to Active Record objects. Prior to 8.1.4.1 and 8.0.5.2, a Rails application that processes attachments with ImageMagick may allow an unauthenticated attacker to write arbitrary files on the server and, when attachments are stored with the Disk service, to read arbitrary files readable by the application process. Those files typically include secret_key_base and credentials for external systems, which may in turn allow escalation to remote code execution or lateral movement to those systems. ImageMagick selects a coder from the content of the file it is given, and some coders act on files named inside the image rather than on the image itself. Active Storage constrained none of ImageMagick’s coders, and the ImageMagick analyzer runs when a file is attached, so an attacker who can upload a crafted file may be able to invoke one. Attaching the upload is sufficient; no variant, preview, or analyze call is required. One specific attack chain has been reported, but other attack chains may exist. An application is affected when it uses ImageMagick for Active Storage image processing through config.active_storage.variant_processor = :mini_magick, runs ImageMagick under a security policy that does not already deny the involved coders, and allows uploads from untrusted users. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.
Description quoted from the CVE record (assigned by GitHub_M, published 2026-11-10).
Weakness: CWE-1188: Initialization of a Resource with an Insecure Default
How it can be exploited
Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Public exploit evidence (Exploit Observer)
Exploit Observer has no public exploit code naming this CVE. Check Exploit Observer for anything new.
Live scores
- EPSS
- 0.009
low predicted chance of attack - VEDAS
- 0.052
little exploit evidence - On CISA KEV
- Not listed
- Detection rule
- No public rule yet
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| rails | version >= 8.1, < 8.1.4.1 version < 8.0.5.2 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
How to fix it
No fixed version or vendor advisory is listed in the CVE record yet. Watch the vendor’s security page.
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
Advisories on this CVE
- Hacker News recap reports OpenSSH SSHole exploitation attempts (full advisory)
- Critical Rails Active Storage flaw lets crafted ImageMagick uploads write server files (full advisory)
References
Other references
- https://github.com/rails/rails/security/advisories/GHSA-f3w6-w445-fwh9 (x_refsource_CONFIRM)
- https://github.com/rails/rails/commit/468aa9a93fc98f5476b6821770f4ccfcb7f7d328 (x_refsource_MISC)
- https://github.com/rails/rails/commit/ea8c40121ce53a3d0255cd4eb6d13bfe3bc01776 (x_refsource_MISC)
- https://github.com/rails/rails/releases/tag/v8.0.5.2 (x_refsource_MISC)
- https://github.com/rails/rails/releases/tag/v8.1.4.1 (x_refsource_MISC)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.
Supporting partners
