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CVE-2026-66066PATCHED
rubygems · activestorage

Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing

Description

Action Pack is a framework for handling and responding to web requests. In versions prior to 7.2.3.2, 8.0.5.1 and 8.1.3.1, Active Storage does not disable libvips operations marked unsafe for untrusted content, allowing a crafted upload to invoke such an operation. Consuming applications are affected when configured to use libvips and accept image uploads from untrusted users. An unauthenticated attacker may exploit this behavior to read arbitrary files accessible to the Rails process, including environment variables and application secrets. Exposure of credentials such as secret_key_base or external-service tokens may enable remote code execution or lateral movement. This issue has been fixed in versions 7.2.3.2, 8.0.5.1 and 8.1.3.1.

Affected Products

VendorProductVersions
rubygemsactivestorage< 7.2.3.2, >= 8.0.0.beta1, < 8.0.5.1, >= 8.1.0.beta1, < 8.1.3.1

Also Affects

Downstream vendors/products affected by this vulnerability

VendorProductSourceConfidence
rubygemsactivestorageGHSA85%

References

  • https://github.com/rails/rails/security/advisories/GHSA-xr9x-r78c-5hrm(x_refsource_CONFIRM)
  • https://github.com/rails/rails/commit/1c01bb587206ee6eb0e1179c2cef96a6a47acb1e(x_refsource_MISC)
  • https://github.com/rails/rails/commit/349e7a5d5b4b715af1e416db824f3c078a7d59e5(x_refsource_MISC)
  • https://github.com/rails/rails/commit/d79b7f4aa17dec8ce4960fef05733c8c0c7ef49a(x_refsource_MISC)
  • https://github.com/rails/rails/releases/tag/v7.2.3.2(x_refsource_MISC)
  • https://github.com/rails/rails/releases/tag/v8.0.5.1(x_refsource_MISC)
  • https://github.com/rails/rails/releases/tag/v8.1.3.1(x_refsource_MISC)
  • https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activestorage/CVE-2026-66066.yml(x_refsource_MISC)
  • https://thehackernews.com/2026/07/critical-rails-flaw-could-let.html(x_refsource_MISC)

Related News (10 articles)

Tier D
Help Net Security2h ago
KindaRails2Shell threatens Ruby on Rails apps (CVE-2026-66066)
→ No new info (linked only)
Tier B
CERT-FR14h ago
Bulletin d'actualité CERTFR-2026-ACT-033 (03 août 2026)
→ No new info (linked only)
Tier D
BleepingComputer2d ago
Rails patches critical Active Storage flaw with RCE potential
→ No new info (linked only)
Tier D
SecurityWeek2d ago
Ruby on Rails Patches Critical Vulnerability
→ No new info (linked only)
Tier D
Heise Security2d ago
Schlüsselklau bei Ruby on Rails – Kritische Lücke mit präparierten Bildern
→ No new info (linked only)
Tier C
oss-security2d ago
Re: Rails CVE-2026-66066: Possible arbitrary file read and remote code execution in Active Storage variant processing
→ No new info (linked only)
Tier B
CCCS Canada3d ago
Rails security advisory (AV26-767)
→ No new info (linked only)
Tier C
VulDB3d ago
CVE-2026-66066 | Rails prior 7.2.3.2/8.0.5.1/8.1.3.1 Active Storage unrestricted upload
→ No new info (linked only)
Tier E
Lobsters Security3d ago
KindaRails2Shell - Critical RCE in Rails via Active Storage (CVE-2026-66066)
→ No new info (linked only)
Tier E
Reddit r/netsec4d ago
KindaRails2Shell: arbitrary file read to RCE in Rails Active Storage via libvips (CVE-2026-66066)
→ No new info (linked only)
CISA KEV❌ No
Actively exploited❌ No
Patch available
activestorage@7.2.3.2activestorage@8.0.5.1activestorage@8.1.3.1
CWECWE-1188
PublishedJul 30, 2026
Tags
GHSA-xr9x-r78c-5hrmrubygems
Trending Score74
Source articles10
Independent10
Info Completeness0/14
Missing: cve_id, title, description, vendor, product, versions, cvss, epss, cwe, kev, exploit, patch, iocs, mitre_attack

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Verification

State: unverified
Confidence: 0%

Vulnerability Timeline

CVE Published
Jul 30, 2026
Discovered by ZDM
Jul 30, 2026
Patch Available
Aug 1, 2026