CVE-2026-39406
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · unedited@hono/node-server allows running the Hono application on Node.js. Prior to 1.19.13, 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. This vulnerability is fixed in 1.19.13.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIn @hono/node-server versions prior to 1.19.13, serveStatic normalizes paths with repeated slashes (e.g., //) while route-based middleware (like /admin/*) may not match these normalized paths. This inconsistency allows attackers to bypass authorization middleware by inserting double slashes into requests for protected static files.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 1.19.12CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check @hono/node-server versionRun 'npm list @hono/node-server' or check package.json dependencies to see the installed version of @hono/node-serverAffected if The installed version is 1.19.12 or lower (anything <= 1.19.12)
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Verify serveStatic is in useSearch your codebase for imports or usage of 'serveStatic' from '@hono/node-server', typically seen as 'serveStatic({ root: ... })' in your app setupAffected if serveStatic from @hono/node-server is being used to serve static files
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Identify route-based middleware protecting pathsSearch your codebase for middleware patterns that protect routes using wildcards or path prefixes, such as '/admin/*', '/protected/*', or similar route guards that apply to specific path prefixesAffected if Route-based middleware (e.g., /admin/*) exists that should protect static file access
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Test repeated slash bypass in your environmentSend a request with repeated slashes in the path, for example: GET /admin//file.txt or GET /protected//sensitive.png - compare behavior to the normalized path GET /admin/file.txtAffected if Requests with repeated slashes (//) reach static files that should be blocked by route-based middleware, while the normalized path would be blocked
You are affected if @hono/node-server version is <= 1.19.12, you use serveStatic from @hono/node-server, and you have route-based middleware protecting static file paths that can be bypassed using repeated slashes in the request URL.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade @hono/node-server to version 1.19.13 or later. Alternatively, implement path normalization in middleware before authorization checks.
1.19.13 or later
- Upgrade @hono/node-server to version 1.19.13 or later by running: npm install @hono/node-server@^1.19.13
- Verify the upgrade was successful by checking the installed version with: npm list @hono/node-server
- Test that paths with repeated slashes (e.g., //admin/file) are properly handled and matched by route-based middleware
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-39406 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-39406 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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