CVE-2026-66066

CRITICALPre-NVD 9.59.5—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 2.1% (81st percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Weaponized
9.5EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • Public exploit code is available (Metasploit, ssvc poc, public exploit)
CISA-KEV: Not listedEPSS PROB: 2.1%CVSS: 9.5Exploit: Metasploit · ssvc poc · public exploitExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
9.5
EG Score
9.5CRITICALmedium confidence
EG Risk
84
EG Risk 84/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity95% × 45%
Exploitation65% × 40%
Automatability100% × 15%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
2.1%
EPSS %ILE
81st
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

July 30, 2026

Last Modified

September 10, 2026

Advisory Details (10)

Auto-updated Oct 2, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: github_commit, github_release, github.
generic

oss-security - Rails CVE-2026-66066: Possible arbitrary file read and remote code execution in Active Storage variant processing

http://www.openwall.com/lists/oss-security/2026/07/29/9
generic🔴 Active Exploitation

Critical Rails Flaw Could Let Unauthenticated Attackers Read Server Files via Image Uploads

https://thehackernews.com/2026/07/critical-rails-flaw-could-let.html
github Patch Available

Possible arbitrary file read and remote code execution in Active Storage variant processing · Advisory · rails/rails · GitHub

https://github.com/rails/rails/security/advisories/GHSA-xr9x-r78c-5hrm
github_release Patch Available

8.1.3.1

Patch available: rails/rails v8.1.3.1

https://github.com/rails/rails/releases/tag/v8.1.3.1
github_release Patch Available

8.0.5.1

Patch available: rails/rails v8.0.5.1

https://github.com/rails/rails/releases/tag/v8.0.5.1
github_release Patch Available

7.2.3.2

Patch available: rails/rails v7.2.3.2

https://github.com/rails/rails/releases/tag/v7.2.3.2
github_commit

commit d79b7f4aa17d (rails/rails)

Fix landed in rails/rails commit d79b7f4aa17d — awaiting tagged release

https://github.com/rails/rails/commit/d79b7f4aa17dec8ce4960fef05733c8c0c7ef49a
github_commit

commit 349e7a5d5b4b (rails/rails)

Fix landed in rails/rails commit 349e7a5d5b4b — awaiting tagged release

https://github.com/rails/rails/commit/349e7a5d5b4b715af1e416db824f3c078a7d59e5
github_commit

commit 1c01bb587206 (rails/rails)

Fix landed in rails/rails commit 1c01bb587206 — awaiting tagged release

https://github.com/rails/rails/commit/1c01bb587206ee6eb0e1179c2cef96a6a47acb1e
generic

ruby-advisory-db/gems/activestorage/CVE-2026-66066.yml at master · rubysec/ruby-advisory-db · GitHub

https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activestorage/CVE-2026-66066.yml

Vendor Advisories for CVE-2026-66066(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
rails2:6.0.3.7+dfsg-2 ... 2:7.2.3.2+dfsg-2 (72 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
rails2:6.1.7.10+dfsg-1~deb12u1 ... 2:7.2.3.2+dfsg-3 (39 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
rails2:7.2.2.1+dfsg-7 ... 2:7.2.3.2+dfsg-3 (11 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
rails2:7.2.2.1+dfsg-7 ... 2:7.2.3.1+dfsg-1 (8 versions)
  • every version up to 2:7.2.3.2+dfsg-1: fixed in 2:7.2.3.2+dfsg-1
—
RubyGems(1)
PackageVulnerable rangeFix by version rangeDependents
activestorage8.1.0 ... 8.1.3 (7 versions)
  • every version up to 7.2.3.2: fixed in 7.2.3.2
  • 8.0.0.beta1 up to 8.0.5.1: fixed in 8.0.5.1
  • 8.1.0.beta1 up to 8.1.3.1: fixed in 8.1.3.1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 39× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 110 total refreshes for this CVE.

  1. 2026-10-04 23:55 UTCEG score recompute
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Publicly available exploits

(6 references)

Working exploit code is in the public domain (1 Metasploit module) (5 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Metasploitexploit/multi/http/rails_activestorage_vips_rce✓ verified
    First seen Jul 29, 2026

    Ruby on Rails Active Storage Vips Arbitrary File Read and Remote Code Execution

    Open source ↗
  • GitHub PoCHackSpeak/CVE-2026-66066
    First seen Aug 3, 2026

    CVE-2026-66066 (KindaRails2Shell) PoC - Rails Active Storage/libvips arbitrary file read to RCE; for authorized security testing

    Open source ↗
  • GitHub PoCHackSpeak/kindarails2shell-poc
    First seen Aug 3, 2026

    CVE-2026-66066 (KindaRails2Shell) PoC - Rails Active Storage/libvips arbitrary file read to RCE; for authorized security testing

    Open source ↗
  • GitHub PoC0xsha/KindaRails2Shell
    First seen Jul 31, 2026

    CVE-2026-66066 + File Read, RCE, Scanner, Lab

    Open source ↗
  • GitHub PoCrails/rails-forensics-CVE-2026-66066
    First seen Jul 30, 2026
    Open source ↗
  • GitHub PoCZer0SumGam3/CVE-2026-66066-POC
    First seen Jul 29, 2026

    PoC for CVE-2026-66066 in Ruby on Rails

    Open source ↗

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-66066?
CVE-2026-66066 is a critical vulnerability published on July 30, 2026. 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…
When was CVE-2026-66066 disclosed?
CVE-2026-66066 was first published on July 30, 2026, with the most recent update on September 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66066 actively exploited?
CVE-2026-66066 is not currently on CISA's Known Exploited Vulnerabilities catalog. EchelonGraph's EG-KEV model classifies it as weaponized: a functional public exploit exists. FIRST EPSS estimates a 2.1% probability of exploitation in the next 30 days (81st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66066?
CVE-2026-66066 has a CVSS base score of 9.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-66066?
A fix for CVE-2026-66066 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-66066 are linked in the Vendor Advisories panel on this page.

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