{
  "affected": [
    {
      "affectedData": [
        {
          "product": "hono",
          "vendor": "honojs",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 4.12.34"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.34, the built-in CORS middleware, hono/cors, is vulnerable to a regular expression denial of service (ReDoS). During a preflight OPTIONS request, the middleware parses the attacker-controlled Access-Control-Request-Headers header using a whitespace-tolerant regular expression whose backtracking makes its running time quadratic in the input length. Because the header value is bounded only by the deployment\u0027s maximum HTTP header size, a single preflight carrying a long run of whitespace can consume seconds of CPU and block request processing. On runtimes that share one execution thread across requests, this stalls concurrent requests as well, and repeated requests can render the service unresponsive. This affects the default configuration, since the vulnerable path is reached whenever cors() is used with an unset or empty allowHeaders. Applications that set a non-empty allowHeaders are not affected. This issue is fixed in version 4.12.34."
    }
  ],
  "id": "CVE-2026-69207",
  "lastModified": "2026-08-07T21:17:29.847",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-07T21:17:29.847",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/honojs/hono/commit/93fc250d8b4df58ea542cb945171de8013d5e6d5"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/honojs/hono/releases/tag/v4.12.34"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/honojs/hono/security/advisories/GHSA-8j4g-w8fx-2239"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1333"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "hono"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.12.34"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-69207"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-03T20:23:30Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nThe built-in CORS middleware (`hono/cors`) parses the attacker-controlled `Access-Control-Request-Headers` request header during a preflight (`OPTIONS`) request using a regular expression whose running time is quadratic in the input length. A single request carrying a long run of whitespace can consume seconds of CPU, and repeated requests can render the service unresponsive. This parsing runs under the default configuration.\n\n### Details\n\nOn a CORS preflight, when `allowHeaders` is not configured - the default - the middleware reflects and parses the `Access-Control-Request-Headers` value. The parser used a whitespace-tolerant regular expression whose backtracking makes the work grow quadratically (O(n\u00b2)) with the length of the value when it contains a long whitespace sequence without a delimiter.\n\nBecause the header value is bounded only by the deployment\u0027s maximum HTTP header size, a single preflight can block request processing for a noticeable amount of time; on runtimes that share one execution thread across requests, this stalls concurrent requests as well. No authentication, special origin, or user interaction is required.\n\nThis issue arises for any application using `cors()` with the default (or an empty) `allowHeaders`. Applications that set a non-empty `allowHeaders` do not reach the affected path.\n\n### Impact\n\nAn unauthenticated attacker can send preflight requests that each consume disproportionate CPU relative to their size, degrading or denying service. This is a denial-of-service issue only; it does not expose or modify data.",
  "id": "GHSA-8j4g-w8fx-2239",
  "modified": "2026-08-03T20:23:31Z",
  "published": "2026-08-03T20:23:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/security/advisories/GHSA-8j4g-w8fx-2239"
    },
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/commit/93fc250d8b4df58ea542cb945171de8013d5e6d5"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/honojs/hono"
    },
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/releases/tag/v4.12.34"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Hono: ReDoS in CORS middleware via Access-Control-Request-Headers"
}