{"id":"GHSA-f27p-cmv8-xhm6","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\u003e 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) =\u003e {\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) =\u003e {\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","aliases":["CVE-2025-21620"],"modified":"2025-01-07T02:52:55Z","published":"2025-01-06T22:27:09Z","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"},"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"}],"affected":[{"package":{"name":"deno_fetch","ecosystem":"crates.io","purl":"pkg:cargo/deno_fetch"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.1"},{"fixed":"0.204.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/01/GHSA-f27p-cmv8-xhm6/GHSA-f27p-cmv8-xhm6.json"}},{"package":{"name":"deno","ecosystem":"crates.io","purl":"pkg:cargo/deno"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"last_affected":"1.46.3"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/01/GHSA-f27p-cmv8-xhm6/GHSA-f27p-cmv8-xhm6.json"}},{"package":{"name":"deno","ecosystem":"crates.io","purl":"pkg:cargo/deno"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.0.0"},{"fixed":"2.1.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/01/GHSA-f27p-cmv8-xhm6/GHSA-f27p-cmv8-xhm6.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"}]}