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

Summary

### Summary 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*…

Product

go: github.com/getarcaneapp/arcane/backend

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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