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CRITICAL CWE-1188

CVE-2026-66066

Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing

Rails

9.5/ 10
CVSS 4.0
Critical severity
33%
EPSS exploit odds
Chance of exploitation in the next 30 days
Higher than 98% of all CVEs
Not listed
CISA KEV catalog
No confirmed in-the-wild exploitation on CISA's list, but a public proof of concept exists.
Timeline
Published
Jul 30, 2026
Updated
Aug 5, 2026
First covered
Aug 2, 2026
Latest story
3 months ago

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.

CWE-1188Insecure Default Initialization of Resource

Attack profile

Attack vectorNetwork
ComplexityLow
RequirementsPresent
PrivilegesNone
User interactionNone
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Affected products

  • rails< 7.2.3.2>= 8.0.0.beta1, < 8.0.5.1>= 8.1.0.beta1, < 8.1.3.1

References

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