CVE-2026-66066

Description

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.

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EPSS — Exploit Prediction

0.0170

Probability of exploitation

0.75%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1188 CWE-1188

References

Other References

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/rails/rails/security/advisories/GHSA-xr9x-r78c-5hrm 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 http://www.openwall.com/lists/oss-security/2026/07/29/9

Frequently Asked Questions

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.

How do I check if I'm vulnerable to CVE-2026-66066? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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