Auditing 25 public MCP servers: only 2 of 20 serve complete OAuth 2.1, free CLI auditor released
No_Instruction_7657 · reddit · 2026-11-03
The author scanned 25 public MCP endpoints and found poor auth hygiene: only 12/25 enforce authentication, 2 of 8 public servers expose mutating tools without auth, and just 2/20 serve a complete OAuth 2.1 discovery document (common gaps: no PKCE, no resource indicators, no per-tool scopes).
They released a free MIT-licensed CLI auditor:
- npx -y u/patchbay-nebius/agent audit https://mcp.example.com/mcp
- 13 checks via pure HTTP probing + static analysis; no backend, no LLM, nothing phones home
- Context-sensitive severity: public read-only servers like DeepWiki are flagged "info" not "critical"
Of three servers initially flagged critical, Chainflip responded within hours that its no-auth design is intentional (broker tools, user signs on-chain) and was downgraded; the other two are under a 90-day responsible disclosure embargo. Full methodology on the blog.
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