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3.4 KiB
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1 line
3.4 KiB
JSON
{"schema_version":"1.9.0","id":"GHSA-2p2x-hpg8-cqp2","published":"2026-02-09T17:18:52Z","modified":"2026-07-13T07:26:21.863580114Z","aliases":["CVE-2026-25478","PYSEC-2026-2195"],"summary":"Litestar's CORS origin allowlist has a bypass due to unescaped regex metacharacters in allowed origins","details":"### Summary\nCORS origin validation can be bypassed because the allowed-origins allowlist is compiled into a regex without escaping metacharacters (notably .). An allowed origin like https://good.example can match https://goodXexample, resulting in Access-Control-Allow-Origin being set for an untrusted origin\n\n### Details\nCORSConfig.allowed_origins_regex is constructed using a regex built from configured allowlist values and used with fullmatch() for validation. Because metacharacters are not escaped, a malicious origin can match unexpectedly. The check relies on allowed_origins_regex.fullmatch(origin).\n\n### PoC\nServer (poc_cors_server.py)\n\n```\nfrom litestar import Litestar, get\nfrom litestar.config.cors import CORSConfig\n\n@get(\"/c\")\nasync def c() -> str:\n return \"ok\"\n\ncors = CORSConfig(\n allow_origins=[\"https://good.example\"],\n allow_credentials=True,\n)\napp = Litestar([c], cors_config=cors)\n```\n\n`uvicorn poc_cors_server:app --host 127.0.0.1 --port 8002`\n\nClient (poc_cors_client.py)\n\n```\nimport http.client\n\ndef req(origin: str) -> tuple[int, str | None]:\n c = http.client.HTTPConnection(\"127.0.0.1\", 8002, timeout=3)\n c.request(\"GET\", \"/c\", headers={\"Origin\": origin, \"Host\": \"example.com\"})\n r = c.getresponse()\n r.read()\n acao = r.getheader(\"Access-Control-Allow-Origin\")\n c.close()\n return r.status, acao\n\nprint(\"evil:\", req(\"https://evil.example\"))\nprint(\"bypass:\", req(\"https://goodXexample\")) \n```\n\nExpected (vulnerable behavior):\n\nOrigin: https://evil.example → no ACAO\nOrigin: https://goodXexample → ACAO: https://goodxexample/ (bypass)\n\n### Impact\nType: CORS policy bypass (cross-origin data exposure risk)\nWho is impacted: apps using CORS allowlists to restrict browser cross-origin reads. If allow_credentials=True and authenticated endpoints return sensitive data, an attacker-controlled site can potentially read responses in a victim’s browser session.","affected":[{"package":{"name":"litestar","ecosystem":"PyPI","purl":"pkg:pypi/litestar"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.19.0"},{"fixed":"2.20.0"}]}],"versions":["2.19.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-2p2x-hpg8-cqp2/GHSA-2p2x-hpg8-cqp2.json"}}],"references":[{"type":"WEB","url":"https://github.com/litestar-org/litestar/security/advisories/GHSA-2p2x-hpg8-cqp2"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25478"},{"type":"WEB","url":"https://github.com/litestar-org/litestar/commit/eb87703b309efcc0d1b087dcb12784e76b003d5a"},{"type":"WEB","url":"https://docs.litestar.dev/2/release-notes/changelog.html#2.20.0"},{"type":"PACKAGE","url":"https://github.com/litestar-org/litestar"},{"type":"WEB","url":"https://github.com/litestar-org/litestar/releases/tag/v2.20.0"}],"database_specific":{"cwe_ids":["CWE-942"],"github_reviewed":true,"github_reviewed_at":"2026-02-09T17:18:52Z","nvd_published_at":"2026-02-09T20:15:57Z","severity":"HIGH"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N"}]} |