Active Storage: Possible arbitrary file write and read in image analysis

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.8 · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-122006: 0.74% estimated exploitation activity in the next 30 days; percentile 55.23 (FIRST EPSS, 2026-11-14). This is a model estimate, not proof of exploitation or customer exposure.
• CVE-2026-126082: 0.87% estimated exploitation activity in the next 30 days; percentile 59.37 (FIRST EPSS, 2026-11-12). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact 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.

Details 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 to us, but we do not assume it is the only one that…

Published by the source

12 Nov 2026, 23:46 UTC

Last modified by the source

13 Nov 2026, 00:00 UTC

Source last checked

13 Nov 2026, 06:40 UTC

1. Revision 2 · amended · 13 Nov 2026

   Amended from osv record GHSA-f3w6-w445-fwh9

2. Revision 1 · created · 13 Nov 2026

   Published from ghsa record GHSA-f3w6-w445-fwh9

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# Patch Next advisory brief: CVE-2026-122006

Advisory: Active Storage: Possible arbitrary file write and read in image analysis
IDs: CVE-2026-122006, GHSA-f3w6-w445-fwh9
Record: https://patchnext.com/advisories/cve-2026-122006 (revision 2, source checked 13 Nov 2026, 06:40 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: activestorage 8.1.4.1, 8.0.5.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems activestorage: affected >= 8.1.0.beta1, < 8.1.4.1; < 8.0.5.2; fixed in 8.0.5.2, 8.1.4.1

## Suggested inspection (read-only)
- RubyGems activestorage: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on activestorage.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-f3w6-w445-fwh9 (GitHub-reviewed advisory GHSA-f3w6-w445-fwh9 lists affected ranges: RubyGems activestorage >=8.1.0.beta1 =0 <8.0.5.2)
- Verified: https://osv.dev/vulnerability/GHSA-f3w6-w445-fwh9 (OSV record GHSA-f3w6-w445-fwh9 lists affected ranges: RubyGems activestorage >=8.1.0.beta1 =0 <8.0.5.2 (fixed))

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