CVE-2026-66066
CRITICALEPSS 98th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v4 Vector
Exploitability
Impact
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
Exploit Intelligence
Very high risk: more likely to be exploited than 98% of all known CVEs.
References
Related Vulnerabilities
Other CWE-1188 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2020-13927 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2023-27524 | High | 8.9 | 97% | KEV | - |
| CVE-2022-24706 | Critical | 9.8 | 93% | KEV | Fix |
| CVE-2020-11532 | Critical | 9.8 | 77% | - | Fix |
| CVE-2018-16752 | High | 8.8 | 43% | - | - |
| CVE-2020-14011 | Critical | 9.8 | 29% | - | - |
Common questions
How do I fix CVE-2026-66066?
Upgrade rails on debian unstable to 2:7.2.3.2+dfsg-1 or later.
Is CVE-2026-66066 being actively exploited?
Not that we know of. CVE-2026-66066 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 27.9% is the estimated probability that it will be exploited in the next 30 days. That is higher than 98% of all scored CVEs.
How severe is CVE-2026-66066?
CVE-2026-66066 has a CVSS v4 base score of 9.5, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-66066 affect?
Published advisories record a fix for rails (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-66066
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-10.