CVE-2026-66066: Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 26.5%
EPSS score, percentile 98 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 9.5 Critical
CVSS v4.0 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- < 7.2.3.2
- >= 8.0.0.beta1, < 8.0.5.1
- >= 8.1.0.beta1, < 8.1.3.1
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
What to do
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | < 7.2.3.2 |
| Affected | >= 8.0.0.beta1, < 8.0.5.1 |
| Affected | >= 8.1.0.beta1, < 8.1.3.1 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
About this vulnerability
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…
Summary: CVE record, as of .
- CISA has not added CVE-2026-66066 to its Known Exploited Vulnerabilities (KEV) catalog, as of 28 Oct 2026.
- The CVE record was published on 30 Jul 2026.
- The CVE record carries a CVSS v4.0 base score of 9.5 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 26.5% (percentile 98), as of 28 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
- CISA's SSVC assessment in the CVE record: exploitation poc, automatable yes, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.
Description
Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
Weakness
- CWE-1188: Insecure Default Initialization of Resource
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
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
Known exploited Rails vulnerabilities
- CVE-2019-5418: Rails Ruby on Rails Path Traversal Vulnerability
- CVE-2014-0130: Ruby on Rails Directory Traversal Vulnerability
- CVE-2016-0752: Ruby on Rails Directory Traversal Vulnerability