CVE-2026-66066 CRITICAL

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

Vendor Rails
Product rails
Weakness CWE-1188
Published July 30, 2026
Last update August 1, 2026

CVSS base score

9.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS 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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

July 30, 2026 CVE published
August 1, 2026 Record updated