CVE-2026-66066 Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing
An unauthenticated attacker can read arbitrary files and potentially execute code via crafted image uploads in Rails Active Storage when libvips is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-66066?
CVE-2026-66066 is a critical path traversal vulnerability in rails, published on 30 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-1188
Which versions are affected by CVE-2026-66066?
6 open source packages ship an affected version, including activestorage.
| Package | Affected | Fixed in |
|---|---|---|
activestorage RubyGems | All versions | 7.2.3.2 |
activestorage RubyGems | All versions | 7.2.3.2 |
activestorage RubyGems | From 8.0.0.beta1 | 8.0.5.1 |
activestorage RubyGems | From 8.0.0.beta1 | 8.0.5.1 |
activestorage RubyGems | From 8.1.0.beta1 | 8.1.3.1 |
activestorage RubyGems | From 8.1.0.beta1 | 8.1.3.1 |
How do I fix CVE-2026-66066?
Upgrade activestorage to a fixed version for your release line: 7.2.3.2, 8.0.5.1 or 8.1.3.1.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-66066 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-66066 exists.
Public exploit code: 1 Metasploit module and 7 proofs of concept on GitHub.
Sources
Also known as DEBIAN-CVE-2026-66066, GHSA-xr9x-r78c-5hrm, MINI-7f33-vgrw-r7jw, MINI-gcm3-57wr-92c6, UBUNTU-CVE-2026-66066.