CVE-2026-66066

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

Published Jul 30, 2026 CVSS 4.0 · 9.5 Critical EPSS 32.9% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4829-1 rails security update
Debian DSA Debian DSA DSA-6546-1 rails security update
Github GHSA Github GHSA GHSA-xr9x-r78c-5hrm Active Storage has possible arbitrary file read and remote code execution in Active Storage variant processing
History
Type Values Removed Values Added
References
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-434
References
Metrics threat_severity

None

cvssV3_1

{'score': 8.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L'}

threat_severity

Important

Type Values Removed Values Added
First Time appeared Rails
Rails rails
Vendors & Products Rails
Rails rails
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing
Weaknesses CWE-1188
References
Metrics cvssV4_0

{'score': 9.5, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Aug 5, 2026, 1:46 PM
Reserved
Jul 23, 2026, 11:25 PM
Status
Awaiting Analysis
Published
Jul 30, 2026, 7:18 PM
Modified
Sep 10, 2026, 8:36 PM
Severity
Important
Public date
Jul 30, 2026, 6:32 PM