CVE-2026-55837

Name of the Vulnerable Software and Affected Versions dbt-mcp version 1.19.1

Description The local OAuth helper FastAPI server bundled with dbt-mcp exposes the 'GET /dbt platform context' endpoint without authentication or host-origin validation. After a user completes the OAuth login flow, this endpoint returns the full DbtPlatformContext object, which includes the user's access token and refresh token for the dbt Platform API. An attacker with co-located process access on the same host, or one who can direct the victim's browser to the helper origin via DNS rebinding (a technique where a domain name is mapped to a different IP address to bypass same-origin policies), can silently exfiltrate these tokens. The stolen access token provides full dbt Cloud API access, while the refresh token allows for persistent unauthorized access. This issue is a Missing Authentication for Critical Function.

Recommendations For version 1.19.1, implement the TrustedHostMiddleware to restrict allowed hosts to "localhost" and "127.0.0.1", and modify the 'GET /dbt platform context' endpoint to redact the decoded access token from the response.