{"id":"ghsa-ghsa-vqqp-x5qm-5qp4","seq":661318,"kind":"advisory","title":"FastMCP MCP client wrappers construct M2M OAuth providers without issuer binding — client secret redirectable to attacker-advertised authorization server","url":"https://github.com/advisories/GHSA-vqqp-x5qm-5qp4","permalink":"https://vulnpulse.app/items/ghsa-ghsa-vqqp-x5qm-5qp4","summary":"影響: pip:fastmcp >= 4.0.0a1, < 4.1.2 → 4.1.2, pip:fastmcp-slim >= 4.0.0a1, < 4.1.2 → 4.1.2\nMaintainer assessment and remediation This report is accepted as a FastMCP credential-binding vulnerability. Affected versions of the OAuth client credentials providers do not expose the authorization-server issuer that owns pre-registered credentials. An untrusted or compromised MCP server can therefore advertise a different authorization server and receive the client secret or a signed assertion. Signing keys themselves remain local; assertion replayability depends on the assertion source and…","severity":"medium","techs":["python"],"cves":[],"tags":["GHSA-vqqp-x5qm-5qp4","fastmcp","fastmcp-slim"],"source":{"id":"ghsa","name":"GitHub Advisory Database"},"published_at":"2026-10-23T21:31:30.000Z","fetched_at":"2026-10-24T04:50:51.468Z"}