CVE-2026-29045
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 · uneditedHono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.12.4, when using serveStatic together with route-based middleware protections (e.g. app.use('/admin/*', ...)), inconsistent URL decoding allowed protected static resources to be accessed without authorization. The router used decodeURI, while serveStatic used decodeURIComponent. This mismatch allowed paths containing encoded slashes (%2F) to bypass middleware protections while still resolving to the intended filesystem path. This issue has been patched in version 4.12.4.
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 confidenceHono framework versions before 4.12.4 have an authorization bypass where serveStatic uses decodeURIComponent while the router uses decodeURI. This inconsistency allows paths containing URL-encoded slashes (%2F) to bypass route-based middleware protections (e.g., app.use('/admin/*', ...)) while still resolving to protected static files on the filesystem.
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< 4.12.4CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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 framework versionRun `npm list hono` or `npm list @hono/node-server` to view the installed version, or inspect package.jsonAffected if Version is below 4.12.4
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Verify serveStatic middleware is in useSearch your codebase for serveStatic imports from @hono/node-server or hono/middleware, and confirm the middleware is appliedAffected if serveStatic is configured and serving static files
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Identify route-based middleware protectionsSearch for app.use() calls that protect specific path prefixes (e.g., app.use('/admin/*', ...), app.use('/protected/*', ...))Affected if Route middleware protections exist on certain path patterns
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Confirm static files served from protected pathsCheck the serveStatic configuration (e.g., basePath, root directory) and compare against paths protected by app.use() middlewareAffected if Static files are served from directories that route middleware intends to protect
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Test for decode inconsistencyMake a request using a URL-encoded slash such as /admin%2Ffile.txt - if it returns the static file while being blocked by the /admin/* route pattern, the bypass is presentAffected if Request with %2F returns protected static file while route middleware blocks the equivalent /admin/ path
You are affected if Hono version is below 4.12.4 AND you use serveStatic to serve files from directories that are also protected by route-based middleware patterns.
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 · scoped4.12.4
Upgrade Hono to version 4.12.4 or later to apply the patched URL decoding consistency fix.
Hono version 4.12.4 or later
- Check the current version of Hono in your project by running `npm list hono` or viewing package.json
- Update the Hono dependency in package.json to version 4.12.4 or higher (e.g., change "hono": "^4.12.3" to "hono": "^4.12.4")
- Run `npm install` or `yarn install` to update Hono to the patched version
- Verify the installation was successful by running `npm list hono` to confirm version 4.12.4 or later is installed
- Test that static file serving and route-based middleware protections work correctly after the update
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
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-29045 — 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-2026-29045 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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