CVE-2026-24398: Hono Hono IPv4 Address Validation Bypass Vulnerability

MODERATE
Advisory Identifier: GHSA-r354-f388-2fhh
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CVSS 4.8
CWE-185
Published
Advisory Summary

CVE-2026-24398 is a MODERATE (CVSS 4.8) hono ipv4 address validation bypass vulnerability (CWE-185: Incorrect Regular Expression) affecting Hono libraries in the npm ecosystem. The issue involves hono ipv4 address validation bypass in ip restriction middleware allows ip spoofing. Remediation is available by upgrading affected packages to version 4.11.7.

CVE-2026-24398 at a Glance

CVE Identifier CVE-2026-24398
GHSA Identifier GHSA-r354-f388-2fhh
Severity MODERATE
CVSS v3.1 Base Score 4.8
CWE Classification CWE-185: Incorrect Regular Expression
Affected Product Hono
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 4.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-24398

To remediate this vulnerability, upgrade all affected Hono dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

hono fixed: 4.11.7 
npm install hono@4.11.7
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls hono

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-24398, inspect your project dependencies using npm:

npm ls hono

Analyze the terminal output to locate any version of Hono in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.11.7), your application is affected.

Note: The npm ls hono command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-185: Incorrect Regular Expression, where the product specifies a regular expression in a way that causes data to be improperly matched or compared. In Hono, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## Summary IP Restriction Middleware in Hono is vulnerable to an IP address validation bypass. The `IPV4_REGEX` pattern and `convertIPv4ToBinary` function in `src/utils/ipaddr.ts` do not properly validate that IPv4 octet values are within the valid range of 0-255, allowing attackers to craft malformed IP addresses that bypass IP-based access controls. ## Details The vulnerability exists in two components: 1. **Permissive regex pattern:** The `IPV4_REGEX (/^[0-9]{0,3}\.[0-9]{0,3}\.[0-9]{0,3}\.[0-9]{0,3}$/)` accepts octet values greater than 255 (e.g., `999`). 2. **Unsafe binary conversion:** The `convertIPv4ToBinary` function does not validate octet ranges before performing bitwise operations. When an octet exceeds 255, it overflows into adjacent octets during the bit-shift calculation. For example, the IP address `1.2.2.355` is accepted and converts to the same binary value as 1.2.3.99: * `355` = `256 + 99` = `0x163` * After bit-shifting: `(1 << 24) + (2 << 16) + (2 << 8) + 355` = `0x01020363` = `1.2.3.99` ## Impact An attacker can bypass IP-based restrictions by crafting malformed IP addresses: * **Blocklist bypass:** If `1.2.3.0/24` is blocked, an attacker can use `1.2.2.355` (or similar) to bypass the restriction. * **Allowlist bypass:** Requests from unauthorized IP ranges may be incorrectly permitted. This is exploitable when the application relies on client-provided IP addresses (e.g., `X-Forwarded-For header`) for access control decisions. ## Affected Components * IP Restriction Middleware * `src/utils/ipaddr.ts`: `IPV4_REGEX`, `convertIPv4ToBinary`, `distinctRemoteAddr`

CVE-2026-24398 Affected Hono Versions

1 component(s)
Fixed Versions:
4.11.7
Product / Package Ecosystem Affected Versions Fixed Version
hono
npm/hono
npm
< 4.11.7
4.11.7

References

GitHub Advisory / Wiki ADVISORY
https://github.com/honojs/hono/security/advisories/GHSA-r354-f388-2fhh
NVD — CVE-2026-24398 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-24398
Security Fix Commit FIX COMMIT
https://github.com/honojs/hono/commit/edbf6eea8e6c26a3937518d4ed91d8666edeec37
Hono Source Repository REPOSITORY
https://github.com/honojs/hono
Hono Release RELEASE
https://github.com/honojs/hono/releases/tag/v4.11.7

Frequently Asked Questions

What is CVE-2026-24398?
CVE-2026-24398 is a security vulnerability in Hono involving Hono IPv4 address validation bypass in IP Restriction Middleware allows IP spoofing under CWE-185: Incorrect Regular Expression.
Which Hono versions are affected?
Affected versions include releases prior to 4.11.7 across affected packages: hono.
What version fixes CVE-2026-24398?
Upgrading to 4.11.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is hono affected?
Yes, hono is affected in releases prior to 4.11.7. Upgrade your dependency to 4.11.7 or later.
What is the CVSS score of CVE-2026-24398?
CVE-2026-24398 has a CVSS v3.1 base score of 4.8 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2026-24398?
CVE-2026-24398 is classified under CWE-185: Incorrect Regular Expression (The product specifies a regular expression in a way that causes data to be improperly matched or compared.).
How can I check npm dependencies for CVE-2026-24398?
Run the dependency tree command: 'npm ls hono'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-r354-f388-2fhh",
  "modified" : "2026-01-29T03:39:00Z",
  "published" : "2026-01-27T19:01:43Z",
  "aliases" : [ "CVE-2026-24398" ],
  "summary" : "Hono IPv4 address validation bypass in IP Restriction Middleware allows IP spoofing",
  "details" : "## Summary\n\nIP Restriction Middleware in Hono is vulnerable to an IP address validation bypass. The `IPV4_REGEX` pattern and `convertIPv4ToBinary` function in `src/utils/ipaddr.ts` do not properly validate that IPv4 octet values are within the valid range of 0-255, allowing attackers to craft malformed IP addresses that bypass IP-based access controls.\n\n## Details\n\nThe vulnerability exists in two components:\n\n1. **Permissive regex pattern:** The `IPV4_REGEX (/^[0-9]{0,3}\\.[0-9]{0,3}\\.[0-9]{0,3}\\.[0-9]{0,3}$/)` accepts octet values greater than 255 (e.g., `999`).\n2. **Unsafe binary conversion:** The `convertIPv4ToBinary` function does not validate octet ranges before performing bitwise operations. When an octet exceeds 255, it overflows into adjacent octets during the bit-shift calculation.\n\nFor example, the IP address `1.2.2.355` is accepted and converts to the same binary value as 1.2.3.99:\n\n* `355` = `256 + 99` = `0x163`\n* After bit-shifting: `(1 << 24) + (2 << 16) + (2 << 8) + 355` = `0x01020363` = `1.2.3.99`\n\n## Impact\n\nAn attacker can bypass IP-based restrictions by crafting malformed IP addresses:\n\n* **Blocklist bypass:** If `1.2.3.0/24` is blocked, an attacker can use `1.2.2.355` (or similar) to bypass the restriction.\n* **Allowlist bypass:** Requests from unauthorized IP ranges may be incorrectly permitted.\n\nThis is exploitable when the application relies on client-provided IP addresses (e.g., `X-Forwarded-For header`) for access control decisions.\n\n## Affected Components\n\n* IP Restriction Middleware\n* `src/utils/ipaddr.ts`: `IPV4_REGEX`, `convertIPv4ToBinary`, `distinctRemoteAddr`",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "hono"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.11.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/honojs/hono/security/advisories/GHSA-r354-f388-2fhh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-24398"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/honojs/hono/commit/edbf6eea8e6c26a3937518d4ed91d8666edeec37"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/honojs/hono"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/honojs/hono/releases/tag/v4.11.7"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-185" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-27T19:01:43Z",
    "nvd_published_at" : "2026-01-27T19:16:16Z"
  }
}