What is CVE-2026-66066?
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.
Timeline
- 2026-07-30Published to the U.S. National Vulnerability Database (NVD)
- 2026-09-10NVD record last updated
Affected product
See advisory
Remediation Steps
- Apply Ruby on Rails security patches addressing Active Storage file exposure
- Audit application logs for unauthorized image upload requests
- Rotate all exposed secrets: secret_key_base, Rails master key, database passwords, cloud storage credentials
- Review and restrict file permissions on application servers to prevent arbitrary file reads
- Consider adding authentication requirements to image upload endpoints if not already present
References
Referenced in our briefings & reports
- Vulnerability Priority Report – Week 4 of July 2026 (July 27 – August 2)
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