CVE-2026-15074: @fastify/static vulnerable to route guard bypass via path traversal
@fastify/static is vulnerable to a bypass of route-based middleware and guards via non-leading .. and %2E%2E path segments. find-my-way does not normalize .. when matching routes, so a request such as /foo/../deep/secret.txt matches the static plugin’s catch-all instead of the guarded /deep/*. The getPathnameForSend helper introduced by the fix for GHSA-x428-ghpx-8j92 only guards against the %2F variant; .. and %2E%2E survive the decodeURI + encodeURI round-trip and are then collapsed away by @fastify/send’s path.normalize before its own traversal guard runs.
Applications that rely on route-based middleware or guards to protect files served by @fastify/static can be bypassed with non-leading dot-dot path segments.
References
- cna.openjsf.org/security-advisories.html
- github.com/advisories/GHSA-83w8-p2f5-377r
- github.com/fastify/fastify-static/commit/db4276f846ba56b21f93768cd6636ee5e2fc58b1
- github.com/fastify/fastify-static/releases/tag/v10.1.1
- github.com/fastify/fastify-static/security/advisories/GHSA-83w8-p2f5-377r
- nvd.nist.gov/vuln/detail/CVE-2026-15074
Code Behaviors & Features
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