{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "0"
                  },
                  {
                    "fixed": "4.13.16"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StringRangeExpression"
              },
              {
                "range": [
                  {
                    "fixed": "34f90432a1794b28e52802670efcd01963f716d6"
                  }
                ],
                "source": "REFERENCES_COMMIT"
              },
              {
                "original_tag": "v4.13.16",
                "range": [
                  {
                    "fixed": "c91b60a251186fb024557c6d55a11d8e388f179c"
                  }
                ],
                "source": "REFERENCES_TAG"
              }
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "c91b60a251186fb024557c6d55a11d8e388f179c"
            },
            {
              "fixed": "34f90432a1794b28e52802670efcd01963f716d6"
            }
          ],
          "repo": "https://github.com/honojs/hono",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-4m76-xfj5-7975"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-288"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126357.json"
  },
  "details": "Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.13.16, mount() and app.mount() can remove a dynamic mount prefix using the route-pattern length rather than the matched-prefix length, allowing a crafted path to be forwarded as a protected inner route while the outer application routes the original path. Since 4.12.21, rebuilding the forwarded URL from the decoded pathname can also convert a decoded backslash to a slash and collapse parent-directory segments, again causing the mounted application to receive a protected path. An unauthenticated client can use either applicable path transformation to reach a mounted route without authentication or authorization middleware scoped to a subpath inside the mount prefix. This issue is fixed in version 4.13.16.",
  "id": "CVE-2026-126357",
  "modified": "2026-11-14T02:30:48.730162560Z",
  "published": "2026-11-12T22:18:46.437Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/releases/tag/v4.13.16"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126357.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/honojs/hono/security/advisories/GHSA-4m76-xfj5-7975"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-126357"
    },
    {
      "type": "FIX",
      "url": "https://github.com/honojs/hono/commit/34f90432a1794b28e52802670efcd01963f716d6"
    }
  ],
  "schema_version": "1.9.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Hono: `mount()` and `app.mount()` can forward a path that bypasses middleware scoped inside the mount prefix"
}