Rapid7 Analysis: KindaRails2Shell (CVE-2026-66066)

Overview On July 29, 2026, the Ruby on Rails project published a security advisory for CVE-2026-66066 , an arbitrary file read in Active Storage applications that use the Vips image processor with untrusted uploads. The affected Active Storage ranges are < 7.2.3.2 , >= 8.0, < 8.0.5.1 , and >= 8.1, < 8.1.3.1 . Vips is the default Active Storage variant processor for applications that load Rails 7.0 or later defaults. Rails 6 applications are affected only when they explicitly configure Vips. Our Emergent Threat Response blog covers the affected versions, mitigation guidance, and current exploit