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HonoApplication

CVE-2026-44455

MEDIUM · 6.1 CVSS v3.1 Published 2026-05-13
Fix available
A fix is available. Upgrade to 4.12.16 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

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 is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.16, Improper handling of JSX element tag names in hono/jsx allowed unvalidated tag names to be directly inserted into the generated HTML output. When untrusted input is used as a tag name via the programmatic jsx() or createElement() APIs during server-side rendering, specially crafted values may break out of the intended element context and inject unintended HTML. This vulnerability is fixed in 4.12.16.

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 confidence

Hono framework versions prior to 4.12.16 have an XSS vulnerability in the hono/jsx component where unvalidated tag names from user input are directly inserted into HTML output during server-side rendering via the jsx() or createElement() APIs, allowing attackers to break out of element contexts and inject arbitrary HTML.

MitigationUpgrade Hono to version 4.12.16 or later. Validate and sanitize any user-supplied input used as JSX tag names before passing to jsx() or createElement() APIs in server-side rendering contexts.

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
HonoApplication
Affected:< 4.12.16

CVSS 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
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Hono version
    Check package.json or run 'npm list hono' or 'pnpm list hono' to see the installed version
    Affected if Version is less than 4.12.16
  2. Locate jsx/createElement usage in SSR code
    Search codebase for imports from 'hono/jsx' and usage of jsx() or createElement() functions in server-side rendering contexts
    Affected if These APIs are used in server-side rendering code paths
  3. Find user input flowing to tag name parameter
    Audit code that passes the first argument to jsx() or createElement() - this is the tag name - and trace whether any user-supplied input (request parameters, headers, body, URL path segments) reaches this parameter unsanitized
    Affected if Unsanitized user input is passed as the tag name argument to jsx() or createElement()
  4. Test for injection in rendered output
    Supply a crafted value as a tag name (e.g., '<img src=x onerror=alert(1)>') and inspect the HTML response from server-side rendering to see if it renders as raw HTML instead of being escaped
    Affected if User-supplied tag names render as unescaped HTML in the response

You are affected if you run Hono version below 4.12.16 AND use jsx() or createElement() in server-side rendering with user input as the tag name parameter.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 4.12.16 or later
Fixed in 4.12.16
Interim mitigation

Upgrade Hono to version 4.12.16 or later. Validate and sanitize any user-supplied input used as JSX tag names before passing to jsx() or createElement() APIs in server-side rendering contexts.

Recommended fix High confidence

4.12.16

  1. Check current Hono version by running `npm list hono` or viewing package.json
  2. Update package.json to specify Hono version 4.12.16 or later: `npm install hono@^4.12.16` or `yarn add hono@^4.12.16`
  3. Run `npm install` or `yarn` to install the updated dependency
  4. Verify the upgrade was successful by running `npm list hono` and confirming version 4.12.16 or higher is installed
  5. Test the application to ensure the upgrade does not break existing functionality
Caveat No breaking changes specifically mentioned for this security fix; standard regression testing recommended

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Hono Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-44455 in production — separate from our analysis above.

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What this is

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What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data