Answer in brief
CVE-2026-66066 records a Critical severity (CVSS 9.5) vulnerability in Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing. The current sources do not mark it as known exploited. The current feed maps rails/rails (generic), activestorage (rubygems), activestorage (rubygems), activestorage (rubygems). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2026-66066 records a Critical severity (CVSS 9.5) vulnerability in Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing. The current sources do not mark it as known exploited. The current feed maps rails/rails (generic), activestorage (rubygems), activestorage (rubygems), activestorage (rubygems). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps rails/rails (generic), activestorage (rubygems), activestorage (rubygems), activestorage (rubygems). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| rails/railsgeneric | < 7.2.3.2 || >= 8.0.0.beta1, < 8.0.5.1 || >= 8.1.0.beta1, < 8.1.3.1 | Not reported |
| activestoragerubygems | <7.2.3.2 | 7.2.3.2 |
| activestoragerubygems | >=8.0.0.beta1,<8.0.5.1 | 8.0.5.1 |
| activestoragerubygems | >=8.1.0.beta1,<8.1.3.1 | 8.1.3.1 |
Published upstream
Jul 30, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 2, 2026
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.
Quoted source text, attributed separately from HOL analysis.
CVSS is 9.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps rails/rails (generic), activestorage (rubygems), activestorage (rubygems), activestorage (rubygems). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| rails/railsgeneric | < 7.2.3.2 || >= 8.0.0.beta1, < 8.0.5.1 || >= 8.1.0.beta1, < 8.1.3.1 | Not reported |
| activestoragerubygems | <7.2.3.2 | 7.2.3.2 |
| activestoragerubygems | >=8.0.0.beta1,<8.0.5.1 | 8.0.5.1 |
| activestoragerubygems | >=8.1.0.beta1,<8.1.3.1 | 8.1.3.1 |
Published upstream
Jul 30, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 2, 2026
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.
Quoted source text, attributed separately from HOL analysis.