CVE-2026-66066Public exploitNetwork attack vector

Arbitrary file read via unsafe libvips loaders

Published Jul 30, 2026 · Updated Jul 30, 2026

Arbitrary file read in Rails Active Storage affected releases allows remote attackers to read server files through crafted uploads. Active Storage passes attacker-controlled uploads to libvips without blocking loaders marked unsafe for untrusted content, allowing HDF5 external datasets to open process-accessible paths. Exposure requires the vips variant processor and image uploads from untrusted users; retrieved secrets can enable code execution or lateral movement.

CVSS severity9.5
Critical
EPSS probability27.86%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Arbitrary file read in Rails Active Storage affected releases allows remote attackers to read server files through crafted uploads. Active Storage passes attacker-controlled uploads to libvips without blocking loaders marked unsafe for untrusted content, allowing HDF5 external datasets to open process-accessible paths. Exposure requires the vips variant processor and image uploads from untrusted users; retrieved secrets can enable code execution or lateral movement.

The record

CVE
CVE-2026-66066
Published
Jul 30, 2026
Updated
Jul 30, 2026
Vendor
Rails
Product
Ruby on Rails
Classifications
CWE-1188, T1005, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 7.2.3.2
  2. Affected versionversion=>= 8.0.0.beta1, < 8.0.5.1
  3. Affected versionversion=>= 8.1.0.beta1, < 8.1.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rails · Ruby on Railsversion=< 7.2.3.2; version=>= 8.0.0.beta1, < 8.0.5.1; version=>= 8.1.0.beta1, < 8.1.3.1

Published CVSS scores

9.5GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1188Initialization of a Resource with an Insecure Default
T1005Data from Local System
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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