Security & Threat Intelligence · 03.08.2026, 17:48 UTC
Rapid7 Analysis: KindaRails2Shell (CVE-2026-66066)
| Schweregrad | info |
|---|---|
| CVE | ↗ |
| Kategorie | Security & Threat Intelligence |
| Quelle | Rapid7 Blog ↗ |
| Veröffentlicht | 03.08.2026 UTC |
Sicherheitsmeldung mit Schweregrad noch nicht bewertet. Betroffene Kennungen: CVE-2026-66066. Technische Details im Tab „Originaltext“; empfohlene Schritte in der Checkliste.
OverviewOn July 29, 2026, the Ruby on Rails project published a security advisory for CVE-2026-66066, an arbitrary file read in Active Storage applications that use the Vips image processor with untrusted uploads. The affected Active Storage ranges are < 7.2.3.2, >= 8.0, < 8.0.5.1, and >= 8.1, < 8.1.3.1. Vips is the default Active Storage variant processor for applications that load Rails 7.0 or later defaults. Rails 6 applications are affected only when they explicitly configure Vips.Our Emergent Threat Response blog covers the affected versions, mitigation guidance, and current exploitation status. This post traces the request from the direct-upload endpoint to the HDF5 read, then shows how the arbitrary file read can expose Rails signing material and become code execution. A vulnerable application can disclose arbitrary files before the attacker has recovered a Rails secret or forged a token. A genuine Active Storage variation_key from the same application, paired with a direct-upload blob whose stored content_type claims to be an image, is enough to reach a libvips loader that turns a crafted MAT/HDF5 file into an arbitrary file-read oracle.We reproduced the published chain against Rails 6.0.6.1, 6.1.7.10, 7.2.3.1, 8.0.5, and 8.1.3, and confirmed that patched 7.2.3.2, 8.0.5.1, and 8.1.3.1 targets block the crafted representation. We also validated a remote code execution (RCE) path that uses only JSON-compatible Hash, Array, and String values in a signed variation. That path reaches Kernel#spawn or Kernel#eval through ImageProcessing's chain builder, and it worked when …