CVE-2026-66066

Summary

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.

Affected Software

Weaknesses

• CWE-1188: CWE-1188: Insecure Default Initialization of Resource

ADP Enrichment

CVE Program Container

Additional References

• http://www.openwall.com/lists/oss-security/2026/07/29/9

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: yes
  • Technical Impact: total

References

• https://github.com/rails/rails/security/advisories/GHSA-xr9x-r78c-5hrm
• https://github.com/rails/rails/commit/1c01bb587206ee6eb0e1179c2cef96a6a47acb1e
• https://github.com/rails/rails/commit/349e7a5d5b4b715af1e416db824f3c078a7d59e5
• https://github.com/rails/rails/commit/d79b7f4aa17dec8ce4960fef05733c8c0c7ef49a
• https://github.com/rails/rails/releases/tag/v7.2.3.2
• https://github.com/rails/rails/releases/tag/v8.0.5.1
• https://github.com/rails/rails/releases/tag/v8.1.3.1
• https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activestorage/CVE-2026-66066.yml
• https://thehackernews.com/2026/07/critical-rails-flaw-could-let.html

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