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HonoApplication

CVE-2026-47674

MEDIUM · 5.3 CVSS v3.1 Published 2026-05-28
Fix available
A fix is available. Upgrade to 4.12.21 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 4.12.21, the ip-restriction middleware (hono/ip-restriction) compares incoming IP addresses against configured deny and allow rules using string equality after partial normalization. Non-canonical IPv6 representations of an address already listed in a static rule — such as compressed forms, explicit-zero forms, or hex-notation IPv4-mapped addresses — do not match the normalized rule entry, causing the rule to be silently skipped. This vulnerability is fixed in 4.12.21.

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

The Hono framework's ip-restriction middleware has a bypass vulnerability where IPv6 addresses in non-canonical forms (compressed, explicit-zero, or hex-notation IPv4-mapped) fail to match statically configured allow/deny rules due to partial normalization and string equality comparison. An attacker could bypass IP restrictions by sending requests with alternative IPv6 representations of a blocked or allowed address.

MitigationUpgrade to Hono version 4.12.21 or later which implements complete IPv6 normalization before comparison.

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:< 4.12.21

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
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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. Check installed Hono version
    Run 'npm list @hono/node-server' or 'npm list hono' to see the installed version, or check package.json for the hono dependency version
    Affected if Installed version is lower than 4.12.21
  2. Verify ip-restriction middleware is in use
    Search codebase for 'ip-restriction' middleware import or usage, typically found in middleware configuration (e.g., import { ipRestriction } from 'hono-ip-restriction' or similar patterns)
    Affected if ip-restriction middleware is configured in the application
  3. Inspect allow/deny rule configuration
    Find where ip-restriction rules are defined - look for allowlist or denylist arrays containing IP addresses, typically in a config file or middleware setup code
    Affected if Static IPv6 addresses or IPv4-mapped IPv6 addresses are configured in allow/deny rules
  4. Confirm IPv6 handling in middleware setup
    Examine the ip-restriction middleware initialization to see if it performs normalization - check if there's any address transformation before comparison
    Affected if The middleware uses string equality comparison without full IPv6 normalization

You are affected if using Hono version below 4.12.21 with the ip-restriction middleware configured with static allow/deny rules that include IPv6 addresses

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 4.12.21 or later
Fixed in 4.12.21
Interim mitigation

Upgrade to Hono version 4.12.21 or later which implements complete IPv6 normalization before comparison.

Recommended fix High confidence

4.12.21

  1. Check the current version of the hono package in your project by running: npm list hono
  2. Update the hono package to version 4.12.21 or later by running: npm install hono@^4.12.21
  3. Verify the update was successful by running: npm list hono
  4. Re-run your test suite to ensure the ip-restriction middleware still functions correctly with the upgrade
  5. Redeploy your application with the updated dependency

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

Fix this in Hono Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

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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-2026-47674 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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