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CVE-2026-57496criticalSecret exposure2026-06-18

CVE-2026-57496: NetLicensing MCP server leaked plaintext API keys via path traversal

Before 0.1.8, the netlicensing_get_product tool in Labs64's netlicensing-mcp put the product number straight into a REST path. Passing ../token reached the token endpoint and skipped the redaction, so a client with a non-admin key could read plaintext API keys, including admin ones.

01.

What it is

get_product() builds the URL as /product/{product_number} with no validation. httpx normalizes /product/../token to /token, so the request goes to NetLicensing's token endpoint.

The response goes through the generic JSON wrapper instead of the token-specific one, so the code that masks APIKEY numbers and SHOP URLs never runs and raw key values come back in the tool output.

A recovered admin token gives broad read, write and delete access to the NetLicensing account. Because the input is a tool argument, a prompt-injected agent could also send it.

02.

How to check

  1. Affected: netlicensing-mcp (PyPI) before 0.1.8.
03.

How to fix

  1. Upgrade netlicensing-mcp to 0.1.8 or later.
  2. If an agent with this server had access to untrusted content, rotate your NetLicensing API keys.
pip show netlicensing-mcp | grep -i version
04.

Sources

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