{"id":"CVE-2023-29159","aliases":["GHSA-v5gw-mw7f-84px","PYSEC-2023-83"],"url":"https://o3.security/vulnerability/CVE-2023-29159","summary":"Starlette has Path Traversal vulnerability in StaticFiles","details":"### Summary\nWhen using `StaticFiles`, if there's a file or directory that starts with the same name as the `StaticFiles` directory, that file or directory is also exposed via `StaticFiles` which is a path traversal vulnerability.\n\n### Details\nThe root cause of this issue is the usage of `os.path.commonprefix()`:\nhttps://github.com/encode/starlette/blob/4bab981d9e870f6cee1bd4cd59b87ddaf355b2dc/starlette/staticfiles.py#L172-L174\n\nAs stated in the Python documentation (https://docs.python.org/3/library/os.path.html#os.path.commonprefix) this function returns the longest prefix common to paths.\n\nWhen passing a path like `/static/../static1.txt`, `os.path.commonprefix([full_path, directory])` returns `./static` which is the common part of `./static1.txt` and `./static`, It refers to `/static/../static1.txt` because it is considered in the staticfiles directory. As a result, it becomes possible to view files that should not be open to the public.\n\nThe solution is to use `os.path.commonpath` as the Python documentation explains that `os.path.commonprefix` works a character at a time, it does not treat the arguments as paths.\n\n### PoC\nIn order to reproduce the issue, you need to create the following structure:\n\n```\n├── static\n│   ├── index.html\n├── static_disallow\n│   ├── index.html\n└── static1.txt\n```\n\nAnd run the `Starlette` app with:\n\n```py\nimport uvicorn\nfrom starlette.applications import Starlette\nfrom starlette.routing import Mount\nfrom starlette.staticfiles import StaticFiles\n\n\nroutes = [\n    Mount(\"/static\", app=StaticFiles(directory=\"static\", html=True), name=\"static\"),\n]\n\napp = Starlette(routes=routes)\n\n\nif __name__ == \"__main__\":\n    uvicorn.run(app, host=\"0.0.0.0\", port=8000)\n```\n\nAnd running the commands:\n\n```shell\ncurl --path-as-is 'localhost:8000/static/../static_disallow/'\ncurl --path-as-is 'localhost:8000/static/../static1.txt'\n```\nThe `static1.txt` and the directory `static_disallow` are exposed.\n\n### Impact\nConfidentiality is breached: An attacker may obtain files that should not be open to the public.\n\n### Credits\nSecurity researcher **Masashi Yamane of LAC Co., Ltd** reported this vulnerability to **JPCERT/CC Vulnerability Coordination Group** and they contacted us to coordinate a patch for the security issue.\n","published":"2023-06-01T00:00:00Z","modified":"2026-08-27T03:57:03.062943034Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"PyPI","name":"starlette","fixedVersion":"0.27.0"}],"fix":{"url":"https://github.com/encode/starlette/commit/1797de464124b090f10cf570441e8292936d63e3","label":"encode/starlette@1797de4"},"references":[{"type":"WEB","url":"https://github.com/encode/starlette/releases/tag/0.27.0"},{"type":"WEB","url":"https://jvn.jp/en/jp/JVN95981715/"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/29xxx/CVE-2023-29159.json"},{"type":"ADVISORY","url":"https://github.com/encode/starlette/security/advisories/GHSA-v5gw-mw7f-84px"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-29159"},{"type":"WEB","url":"https://github.com/encode/starlette/commit/1797de464124b090f10cf570441e8292936d63e3"},{"type":"PACKAGE","url":"https://github.com/encode/starlette"},{"type":"WEB","url":"https://github.com/encode/starlette/blob/4bab981d9e870f6cee1bd4cd59b87ddaf355b2dc/starlette/staticfiles.py#L172-L174"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2023-83.yaml"},{"type":"WEB","url":"https://jvn.jp/en/jp/JVN95981715"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-27T03:57:03.062943034Z"}}