CVE-2025-21620: fetch Authorization Headers Not Dropped When Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-f27p-cmv8-xhm6",
  "modified" : "2025-01-07T02:52:55Z",
  "published" : "2025-01-06T22:27:09Z",
  "aliases" : [ "CVE-2025-21620" ],
  "summary" : "fetch: Authorization headers not dropped when redirecting cross-origin",
  "details" : "### Summary\nWhen you send a request with the `Authorization` header to one domain, and the response asks to redirect to a different domain, Deno's`fetch()` redirect handling creates a follow-up redirect request that keeps the original `Authorization` header, leaking its content to that second domain.\n\n\n### Details\n\nThe [right behavior](https://fetch.spec.whatwg.org/#ref-for-cors-non-wildcard-request-header-name) would be to drop the `Authorization` header instead, in this scenario. The same is generally applied to `Cookie` and `Proxy-Authorization` headers, and is done for not only host changes, but also protocol/port changes. Generally referred to as \"origin\".\n\nThe [documentation](https://docs.deno.com/runtime/reference/web_platform_apis/#:~:text=Deno%20does%20not%20follow%20the,leaking%20authenticated%20data%20cross%20origin.) states: \n> Deno does not follow the same-origin policy, because the Deno user agent currently does not have the concept of origins, and it does not have a cookie jar. This means Deno **does not need** to protect against leaking authenticated data cross origin \n\n### Reproduction\n```ts\nconst ac = new AbortController()\n\nconst server1 = Deno.serve({ port: 3001, signal: ac.signal }, (req) => {\n  return new Response(null, {\n    status: 302,\n    headers: {\n      'location': 'http://localhost:3002/redirected'\n    },\n  })\n})\n\nconst server2 = Deno.serve({ port: 3002, signal: ac.signal }, (req) => {\n  const body = JSON.stringify({\n    url: req.url,\n    hasAuth: req.headers.has('authorization'),\n  })\n  return new Response(body, {\n    status: 200,\n    headers: {'content-type': 'application/json'},\n  })\n})\n\nasync function main() {\n  const response = await fetch(\"http://localhost:3001/\", {\n    headers: {authorization: 'Bearer foo'}\n  })\n  const body = await response.json()\n  \n  ac.abort()\n  \n  if (body.hasAuth) {\n    console.error('ERROR: Authorization header should not be present after cross-origin redirect')\n  } else {\n    console.log('SUCCESS: Authorization header is not present after cross-origin redirect')\n  }\n}\n\nsetTimeout(main, 500)\n```\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "deno_fetch"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.0.1"
      }, {
        "fixed" : "0.204.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "deno"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.46.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "deno"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.1.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/denoland/deno/security/advisories/GHSA-f27p-cmv8-xhm6"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-21620"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/denoland/deno"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-01-06T22:27:09Z",
    "nvd_published_at" : "2025-01-06T23:15:07Z"
  }
}