GHSA-XPCF-PG52-R92G

Vulnerability from github – Published: 2026-04-08 00:17 – Updated: 2026-04-08 15:34
VLAI?
Summary
Hono has incorrect IP matching in ipRestriction() for IPv4-mapped IPv6 addresses
Details

Summary

ipRestriction() does not canonicalize IPv4-mapped IPv6 client addresses (e.g. ::ffff:127.0.0.1) before applying IPv4 allow or deny rules. In environments such as Node.js dual-stack, this can cause IPv4 rules to fail to match, leading to unintended authorization behavior.

Details

The middleware classifies client addresses based on their textual form. Addresses containing ":" are treated as IPv6, including IPv4-mapped IPv6 addresses such as ::ffff:127.0.0.1. These addresses are not normalized to IPv4 before matching.

As a result:

  • IPv4 static rules (e.g. 127.0.0.1) do not match because the raw string differs
  • IPv4 CIDR rules (e.g. 127.0.0.0/8, 10.0.0.0/8) are skipped because the address is treated as IPv6

For example, with:

denyList: ['127.0.0.1']

a request from 127.0.0.1 may be represented as ::ffff:127.0.0.1 and bypass the deny rule.

This behavior commonly occurs in Node.js environments where IPv4 clients are exposed as IPv4-mapped IPv6 addresses.

Impact

Applications that rely on IPv4-based ipRestriction() rules may incorrectly allow or deny requests.

In affected deployments, a denied IPv4 client may bypass access restrictions. Conversely, legitimate clients may be rejected when using IPv4 allow lists.

Severity ?
6.3 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "hono"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.12.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-39409"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-180"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-08T00:17:14Z",
    "nvd_published_at": "2026-04-08T15:16:14Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\n`ipRestriction()` does not canonicalize IPv4-mapped IPv6 client addresses (e.g. `::ffff:127.0.0.1`) before applying IPv4 allow or deny rules. In environments such as Node.js dual-stack, this can cause IPv4 rules to fail to match, leading to unintended authorization behavior.\n\n## Details\n\nThe middleware classifies client addresses based on their textual form. Addresses containing \"`:`\" are treated as IPv6, including IPv4-mapped IPv6 addresses such as `::ffff:127.0.0.1`. These addresses are not normalized to IPv4 before matching.\n\nAs a result:\n\n* IPv4 static rules (e.g. `127.0.0.1`) do not match because the raw string differs\n* IPv4 CIDR rules (e.g. `127.0.0.0/8`, `10.0.0.0/8`) are skipped because the address is treated as IPv6\n\nFor example, with:\n\n`denyList: [\u0027127.0.0.1\u0027]`\n\na request from `127.0.0.1` may be represented as `::ffff:127.0.0.1` and bypass the deny rule.\n\nThis behavior commonly occurs in Node.js environments where IPv4 clients are exposed as IPv4-mapped IPv6 addresses.\n\n## Impact\n\nApplications that rely on IPv4-based `ipRestriction()` rules may incorrectly allow or deny requests.\n\nIn affected deployments, a denied IPv4 client may bypass access restrictions. Conversely, legitimate clients may be rejected when using IPv4 allow lists.",
  "id": "GHSA-xpcf-pg52-r92g",
  "modified": "2026-04-08T15:34:40Z",
  "published": "2026-04-08T00:17:14Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/security/advisories/GHSA-xpcf-pg52-r92g"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-39409"
    },
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/commit/48fa2233bc092f650119f42df043050737cabf39"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/honojs/hono"
    },
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/releases/tag/v4.12.12"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Hono has incorrect IP matching in ipRestriction() for IPv4-mapped IPv6 addresses"
}


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