CVE-2026-90982

/// Technical description

@fastify/static is a Fastify plugin that serves static files from a configured root directory. In versions before 10.1.4, on a case-insensitive filesystem such as Windows or the default macOS volume, a route guard or allowedPath restriction can be bypassed by altering the letter case of a path segment. The route matcher is case-sensitive while the filesystem is not, so a request that changes the case of a protected segment does not match the guarded route and falls through to the static handler, yet the filesystem resolves it to the same protected file. As a result, an unauthenticated request can read a file that a route guard or allowedPath was configured to protect. The issue does not affect case-sensitive filesystems and is not a directory traversal, since nothing is served from outside the configured root. The issue is fixed in @fastify/static 10.1.4, which validates the requested path against its actual on-disk spelling and rejects case-aliased paths before authorization. As a wor

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References