@fastify/static vulnerable to route guard bypass via path traversal

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-15074: 0.67% estimated exploitation activity in the next 30 days; percentile 52.09 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

24 Jul 2026, 16:43 UTC

Last modified by the source

24 Jul 2026, 17:11 UTC

Source last checked

26 Oct 2026, 12:58 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-83w8-p2f5-377r

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-83w8-p2f5-377r

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-15074

Advisory: @fastify/static vulnerable to route guard bypass via path traversal
IDs: CVE-2026-15074, GHSA-83w8-p2f5-377r
Record: https://patchnext.com/advisories/cve-2026-15074 (revision 2, source checked 26 Oct 2026, 12:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @fastify/static 10.1.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @fastify/static: affected <= 10.1.0; fixed in 10.1.1

## Suggested inspection (read-only)
- `npm ls @fastify/static --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @fastify/static.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-83w8-p2f5-377r (OSV record GHSA-83w8-p2f5-377r lists affected ranges: npm @fastify/static >=0 <10.1.1 (fixed))
- Verified: https://github.com/advisories/GHSA-83w8-p2f5-377r (GitHub-reviewed advisory GHSA-83w8-p2f5-377r lists affected ranges: npm @fastify/static >=0 <=10.1.0)

Commands are suggestions: review each one before running it.