CVE-2026-66066
What it is
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.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 30.1% chance of exploitation in the next 30 days (EPSS). Higher than most.
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 30.1% in the next 30 days (EPSS).
- Severity: 9.5 CRITICAL (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 30.1% · EPSS, next 30 days
- Weakness
- CWE-1188
- Record status
- Awaiting Analysis
Attack profile CVSS 4.0 · 9.5
- Attack vector
- Network
- Complexity
- Low
- Attack requirements
- Present
- Privileges needed
- None
- User interaction
- None
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-66066.md and follow it. Check whether this project is affected by CVE-2026-66066. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- 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
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
- http://www.openwall.com/lists/oss-security/2026/08/01/6
- https://ethiack.com/info-hub/research/kindarails2shell-rails-rce-cve-2026-66066
- https://github.com/rails/rails-forensics-CVE-2026-66066