GHSA-wmmm-f939-6g9c is a medium-severity (CVSS 5.3) Path Traversal vulnerability in hono. O3 Security confirms whether GHSA-wmmm-f939-6g9c is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Hono: Middleware bypass via repeated slashes in serveStatic
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
hononpmDescription
Summary
A path handling inconsistency in serveStatic allows protected static files to be accessed by using repeated slashes (//) in the request path.
When route-based middleware (e.g., /admin/*) is used for authorization, the router may not match paths containing repeated slashes, while serveStatic resolves them as normalized paths. This can lead to a middleware bypass.
Details
The routing layer and serveStatic handle repeated slashes differently.
For example:
/admin/secret.txt => matches /admin/*
/admin//secret.txt => may not match /admin/*
However, serveStatic may interpret both paths as the same file location (e.g., admin/secret.txt) and return the file.
This inconsistency allows a request such as:
GET //admin/secret.txt
to bypass middleware registered on /admin/* and access protected files.
The issue has been fixed by rejecting paths that contain repeated slashes, ensuring consistent behavior between route matching and static file resolution.
Impact
An attacker can access static files that are intended to be protected by route-based middleware by using repeated slashes in the request path.
This can lead to unauthorized access to sensitive files under the static root.
This issue affects applications that rely on serveStatic together with route-based middleware for access control.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | hono | all versions | 4.12.12 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hono. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update hono to 4.12.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wmmm-f939-6g9c is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-wmmm-f939-6g9c is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-wmmm-f939-6g9c. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-wmmm-f939-6g9c in your dependencies?
O3 detects GHSA-wmmm-f939-6g9c across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.