17d • 🧠 AI Signals
Your MCP server might be writing credentials to its logs.
Last week's n8n-MCP patch (https://nvd.nist.gov/vuln/detail/CVE-2026-42282) made it concrete: in HTTP mode, every credential passed through a tool call was being written to the server's logs in plaintext, before any redaction kicked in. Bearer tokens, OAuth creds, API keys — all sitting wherever your logs end up, readable by anyone with log access.
Fixed in v2.47.13. Update if you're running it.
But the thing I keep sitting with isn't this one CVE. It's the pattern underneath it.
MCP tool calls move data through a part of the stack ops teams have been treating as "just logs" forever - SIEM ingestion, log aggregators, shared cold storage. None of that infrastructure knows the difference between a debug message and a credential. It just stores whatever shows up.
And the MCP spec, as it stands, has no way to tag a tool argument as *this is a secret, don't log it*. Every server author re-implements redaction on their own. Some get it right. n8n-MCP didn't — they had a silencing layer that was just fragile enough to fail. Most other servers don't have even that.
Which means a lot of us are probably running MCP servers right now that are quietly writing credentials into logs we've never actually looked at.
A question I'm curious about: if you're running an MCP server - in production, in your homelab, anywhere - when was the last time you actually opened its logs and read what shows up when a tool call carries credential material? Drop a thought, a war story, or even just a "huh, I should check" below.
I'll share what I find on mine, and I'm putting together a short follow-up next week with the specific things I'm looking at. More fun if we figure it out together.
— Josh
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Your MCP server might be writing credentials to its logs.
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