Rails prior 7.2.3.2/8.0.5.1/8.1.3.1 Active Storage unrestricted upload

Summaryinfo

A vulnerability was found in Rails. It has been declared as critical. The impacted element is an unknown function of the component Active Storage. Such manipulation leads to unrestricted upload. This vulnerability is listed as CVE-2026-66066. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability was found in Rails and classified as critical. Affected by this issue is some unknown processing of the component Active Storage. The manipulation with an unknown input leads to a unrestricted upload vulnerability. Using CWE to declare the problem leads to CWE-434. The product allows the attacker to upload or transfer files of dangerous types that can be automatically processed within the product's environment. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-66066 since 07/24/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1608.002.

Upgrading to version 7.2.3.2, 8.0.5.1 or 8.1.3.1 eliminates this vulnerability.

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• Rails

Website

• Product: https://github.com/rails/rails/

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