CVE-2026-42461 PoC — Arcane Vulnerable to Unauthenticated Disclosure of Custom Compose Template Content (incl. `.env` secrets)

Source

https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-42461.yaml

Associated Vulnerability

Title: Arcane Vulnerable to Unauthenticated Disclosure of Custom Compose Template Content (incl. `.env` secrets) (CVE-2026-42461)
Description:Arcane is an interface for managing Docker containers, images, networks, and volumes. Prior to version 1.18.0, four GET endpoints under /api/templates* in Arcane's Huma backend are registered without any Security requirement, allowing any unauthenticated network client to list and read the full Compose YAML and .env content of every custom template stored in the instance. Because Arcane's UI exposes a "Save as Template" flow on the project / swarm-stack creation pages that persists the operator's real env content (database passwords, API keys, etc.) verbatim, this missing authorization is an unauthenticated read of operator secrets in practice — not a theoretical info-disclosure. The frontend explicitly treats /customize/templates/* as an authenticated area (PROTECTED_PREFIXES in frontend/src/lib/utils/redirect.util.ts), and every CRUD operation (POST/PUT/DELETE) on the same paths requires a Bearer/API key, so this is a clear backend authorization gap, not intended public access. This issue has been patched in version 1.18.0.

Description

Arcane < 1.18.0 contains an information disclosure caused by missing authorization on /api/templates GET endpoints, letting unauthenticated network clients read sensitive Compose YAML and .env content, exploit requires network access

File Snapshot

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