VULNpocalypse

CVE-2026-66066: Action Pack: Possible arbitrary file read and remote code execution in Active Storage variant processing

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

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.

Description quoted from the CVE record (assigned by GitHub_M, published 2026-07-30).

Weakness: CWE-1188: Insecure Default Initialization of Resource

How it can be exploited

Exploitable over the network with low attack complexity only when specific conditions are present needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. 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

CISA assessment (SSVC): CISA assesses that a public proof of concept exists. Automatable: yes. Technical impact: total.

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-10713, EUVD-2026-51270, GHSA-xr9x-r78c-5hrm

VEDAS cluster: VEDAS:AZTECLION

Exploit Observer links 6 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (6)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (7)

Vulnerability databases and vendor advisories (7)

Catalogue entries, not exploit evidence.

News (1)

166 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.301
likely to be attacked soon
VEDAS
0.983
strong exploit evidence
On CISA KEV
Not listed
Detection rule
None yet

Who is affected

ProductAffectedNot affected
rails railsversion < 7.2.3.2
version >= 8.0.0.beta1, < 8.0.5.1
version >= 8.1.0.beta1, < 8.1.3.1		Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: rails_core_team ruby_on_rails.

How to fix it

No fixed version or vendor advisory is listed in the CVE record yet. Watch the vendor’s security page.

How to detect it

There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.

References

Exploits and technical analysis

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.