CVE-2026-15074 is a high-severity (CVSS 7.5) Path Traversal vulnerability in @fastify/static. A fix is available for @fastify/static — see the affected versions and patch details below.
@fastify/static vulnerable to route guard bypass via path traversal
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-15074 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@fastify/staticnpmDescription
Impact
@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.
Patches
Upgrade to @fastify/static 10.1.1.
Workarounds
Do not use route-based middlewares or guards to protect files served by @fastify/static.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @fastify/static | all versions | 10.1.1npm install @fastify/static@10.1.1 |
Affected Products
fastify-staticfastifyDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @fastify/static, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @fastify/static to 10.1.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-15074 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
Frequently Asked Questions
Is CVE-2026-15074 in your dependencies?
Find it across npm, including transitive dependencies.