Critical 9.5Published Jul 30, 2026

CVE-2026-66066Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing

Updated under an hour ago (Oct 26, 2026, 7:50 PM ET)

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Exploited in the last 30 days

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.

CVSS: 9.5 CRITICAL (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Weakness (CWE): CWE-1188
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Aug 5, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

rails rails rails:rails (from the name)	before 7.2.3.2; from 8.0.0.beta1, < 8.0.5.1; from 8.1.0.beta1, < 8.1.3.1	CNA record

References

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
http://www.openwall.com/lists/oss-security/2026/07/29/9
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.