{"id":"CVE-2025-62727","summary":"Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse","details":"Starlette is a lightweight ASGI framework/toolkit. Starting in version 0.39.0 and prior to version 0.49.1 , an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial‑of‑service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.","aliases":["GHSA-7f5h-v6xp-fcq8","PYSEC-2026-1942"],"modified":"2026-08-12T03:51:48.542248399Z","published":"2025-10-28T20:14:53.655Z","related":["CGA-mwr9-whh6-3ppf","SUSE-SU-2026:22151-1","openSUSE-SU-2025:15696-1","openSUSE-SU-2026:10109-1","openSUSE-SU-2026:20975-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/62xxx/CVE-2025-62727.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-407"]},"references":[{"type":"WEB","url":"https://github.com/Kludex/starlette/releases/tag/0.49.1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/62xxx/CVE-2025-62727.json"},{"type":"ADVISORY","url":"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-62727"},{"type":"FIX","url":"https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5"},{"type":"FIX","url":"https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/kludex/starlette","events":[{"introduced":"65bfd74307f593505aaa4c399f73e4d90cd8aa78"},{"fixed":"4ea6e22b489ec388d6004cfbca52dd5b147127c5"},{"fixed":"69ed26a85956ef4bd0161807eb27abf49be7cd3c"},{"fixed":"7e4b7428f273dbdc875dcd036d20804bcfc7b2ee"}],"database_specific":{"extracted_events":[{"introduced":"0.39.0"},{"fixed":"0.49.1"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["0.49.0","0.48.0","0.47.3","0.47.2","0.47.1","0.47.0","0.46.2","0.46.1","0.46.0","0.45.3","0.45.2","0.45.1","0.45.0","0.44.0","0.43.0","0.42.0","0.41.3","0.41.2","0.41.1","0.41.0","0.40.0","0.39.2","0.39.1","0.39.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-62727.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}