Vulnerability in Ruby on Rails activestorage (July 30, 2026)

unknownpublic exploitCVE-2026-66066

A vulnerability has been discovered in Ruby on Rails activestorage. It allows an attacker to cause remote arbitrary code execution and a breach of data confidentiality.

CSIRTS triage

vendor: Ruby on Rails product: activestorage Remote code execution Information disclosure

What: A vulnerability allows an attacker to cause remote arbitrary code execution and breach data confidentiality.
Who is affected: Deployments using Ruby on Rails activestorage are affected.
Urgency: Remediation is urgent as it involves remote code execution, which can lead to severe impacts.
Action: Upgrade to the patched version of Ruby on Rails activestorage.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: CERT-FR Avis de sécurité (FR · national-cert · site)
Severity: unknown
Published: 2026-07-30
Exploitation: Not in CISA KEV at last sync
Language: Machine-translated to English — verify against the original

Original advisory: https://www.cert.ssi.gouv.fr/avis/CERTFR-2026-AVI-0948/

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Moderate exploitation riskCVE-2026-660661.7% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 75% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-66066	coverage & exploitation status	NVD · CVE.org

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