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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-66066
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-30 19:18:35 UTC
Updated2026-08-01 08:16:30 UTC
DescriptionAction 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.

Risk And Classification

Primary CVSS: v4.0 9.5 CRITICAL from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.017010000 probability, percentile 0.749320000 (date 2026-07-31)

Problem Types: CWE-1188 | CWE-1188 CWE-1188: Insecure Default Initialization of Resource

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary9.5CRITICALCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/C...
4.0CNADECLARED9.5CRITICALCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality
High
Integrity
High
Availability
High
Sub Conf.
High
Sub Integrity
High
Sub Availability
High

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Rails Rails affected < 7.2.3.2 Not specified
CNA Rails Rails affected >= 8.0.0.beta1, < 8.0.5.1 Not specified
CNA Rails Rails affected >= 8.1.0.beta1, < 8.1.3.1 Not specified

References

ReferenceSourceLinkTags
www.openwall.com/lists/oss-security/2026/08/01/6 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
github.com/rails/rails/commit/349e7a5d5b4b715af1e416db824f3c078a7d59e5 [email protected] github.com
github.com/rubysec/ruby-advisory-db/blob/master/gems/activestorage/CVE-2... [email protected] github.com
thehackernews.com/2026/07/critical-rails-flaw-could-let.html [email protected] thehackernews.com
github.com/rails/rails/commit/1c01bb587206ee6eb0e1179c2cef96a6a47acb1e [email protected] github.com
github.com/rails/rails/releases/tag/v7.2.3.2 [email protected] github.com
github.com/rails/rails/releases/tag/v8.1.3.1 [email protected] github.com
github.com/rails/rails/releases/tag/v8.0.5.1 [email protected] github.com
www.openwall.com/lists/oss-security/2026/07/29/9 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
github.com/rails/rails/commit/d79b7f4aa17dec8ce4960fef05733c8c0c7ef49a [email protected] github.com
ethiack.com/info-hub/research/kindarails2shell-rails-rce-cve-2026-66066 af854a3a-2127-422b-91ae-364da2661108 ethiack.com
github.com/rails/rails/security/advisories/GHSA-xr9x-r78c-5hrm [email protected] github.com
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