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Fencer Intel
critical 9.5

CVE-2026-66066 in the critical feed json

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

published 3mo ago modified last mo. also EUVD-2026-51270 , GHSA-xr9x-r78c-5hrm

cvss
9.5
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
32.9%
EPSS 32.9% chance of exploitation in 30 days, percentile 98%
public exploits
1
Metasploit

Summary

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.

Patch / fix

  • rubygems activestorage 7.2.3.2, 8.0.5.1, 8.1.3.1
  • activerecord_project activerecord 7.2.3.2, 8.0.5.1, 8.1.3.1
  • rubyonrails rails 7.2.3.2, 8.0.5.1, 8.1.3.1
  • rails Debian 12 2:6.1.7.10+dfsg-1~deb12u3
  • rails Debian 13 2:7.2.2.2+dfsg-2~deb13u2
  • rails Debian 14 2:7.2.3.2+dfsg-1

debian advisories DEBIAN-CVE-2026-66066

  • hawk2 SLE High Availability Extension 16.0, SLES for SAP applications 16.0 2.7.2+git.1788518533.7d4dadd6-160000.1.1

suse advisories SUSE-SU-2026:24195-1SUSE-SU-2026:24250-1

  • hawk2 openSUSE Tumbleweed 2.7.2+git.1792148770.648dcddb-1.1
  • hawk2 openSUSE Leap 16.0 2.7.2+git.1788518533.7d4dadd6-160000.1.1

opensuse advisories openSUSE-SU-2026:12153-1openSUSE-SU-2026:22068-1

Is CVE-2026-66066 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-66066 updated cvss 8.9

activestorage: Active Storage: Remote Code Execution via Unsafe libvips Operations

  • Red Hat 3scale API Management Platform 2 3scale-amp21/zync, 3scale-amp22/zync, 3scale-amp24/zync, 3scale-amp25/zync, 3scale-amp26/zync, 3scale-amp20/system, +11 more Red Hat Satellite 6 rubygem-activestorage
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (Metasploit exploit/multi/http/rails_activestorage_vips_rce)
  2. Published

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
3mo ago

Exploit prediction

32.90% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

CVSS scores

assigned by version score vector
CNA 4.0 9.5 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
CNA 4.0 9.5 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

Affected packages

ecosystem package affected fixed in
rubygems activestorage
<7.2.3.2
>=8.0.0.beta1, <8.0.5.1
>=8.1.0.beta1, <8.1.3.1
7.2.3.2
8.0.5.1
8.1.3.1

Affected products

  • rails rails

Classification

Weakness
  • CWE-1188 Initialization of a Resource with an Insecure Default
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of rails/rails published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.