Rails patches critical Active Storage flaw with RCE potential

A critical vulnerability, CVE-2026-66066, in the Rails Active Storage component allows unauthenticated attackers to read arbitrary files from a Rails application by uploading a specially crafted image when libvips is used for image processing. If successful, attackers can extract sensitive environment variables such as 'secret_key_base', enabling session forgery, data manipulation, and remote code execution (RCE). The vulnerability affects Active Storage versions prior to 7.2.3.2, 8.0.5.1, and 8.1.3.1, with no workaround available for older libvips versions. Public proof-of-concept exploits have accelerated disclosure and prompted WAF protections from Akamai.

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