CVE-2025-64166

Medium

Description

Mercurius is a GraphQL adapter for Fastify. Prior to version 16.4.0, a cross-site request forgery (CSRF) vulnerability was identified. The issue arises from incorrect parsing of the Content-Type header in requests. Specifically, requests with Content-Type values such as application/x-www-form-urlencoded, multipart/form-data, or text/plain could be misinterpreted as application/json. This misinterpretation bypasses the preflight checks performed by the fetch() API, potentially allowing unauthorized actions to be performed on behalf of an authenticated user. This issue has been patched in version 16.4.0.

SeverityMedium
CVSS5.4
Exploit probability—
ProductMercurius
PublishedMar 5, 2026
First seenMar 5, 2026

How to fix

Update
  • mercurius_project mercurius16.4.0 or later
  • mercurius16.4.0 or later

Affected products

ProductAffected versionsFixed in
mercurius_project mercuriusv < 16.4.016.4.0
mercuriusnpmv < 16.4.016.4.0

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