Medium severity6.1NVD Advisory· Published Apr 3, 2026· Updated Apr 22, 2026
CVE-2026-27124
CVE-2026-27124
Description
FastMCP is the standard framework for building MCP applications. Prior to version 3.2.0, while testing the GitHubProvider OAuth integration, which allows authentication to a FastMCP MCP server via a FastMCP OAuthProxy using GitHub OAuth, it was discovered that the FastMCP OAuthProxy does not properly validate the user's consent upon receiving the authorization code from GitHub. In combination with GitHub’s behavior of skipping the consent page for previously authorized clients, this introduces a Confused Deputy vulnerability. This issue has been patched in version 3.2.0.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
fastmcpPyPI | < 3.2.0 | 3.2.0 |
Affected products
2Patches
Vulnerability mechanics
References
4- github.com/PrefectHQ/fastmcp/security/advisories/GHSA-rww4-4w9c-7733nvdExploitMitigationVendor AdvisoryWEB
- github.com/advisories/GHSA-rww4-4w9c-7733ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-27124ghsaADVISORY
- github.com/jlowin/fastmcp/security/advisories/GHSA-rww4-4w9c-7733ghsaWEB
News mentions
0No linked articles in our index yet.