{"id":"CVE-2025-62727","state":"PUBLISHED","title":"Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse","description":"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.","publishedAt":"2025-10-28T20:14:53.655Z","updatedAt":"2025-11-04T17:41:42.316Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["Kludex starlette"],"affected":[{"vendor":"Kludex","product":"starlette","versions":[{"version":">= 0.39.0, < 0.49.1","status":"affected"}]}],"references":["https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8","https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5","https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c","https://github.com/Kludex/starlette/releases/tag/0.49.1"],"weaknesses":["CWE-407"],"ingestedAt":"2026-10-29T20:09:48.677Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/62xxx/CVE-2025-62727.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-62727","state":"PUBLISHED","datePublished":"2025-10-28T20:14:53.655Z","dateUpdated":"2025-11-04T17:41:42.316Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2025-10-20T19:41:22.742Z"},"containers":{"cna":{"title":"Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Kludex","product":"starlette","versions":[{"version":">= 0.39.0, < 0.49.1","status":"affected"}]}],"references":[{"url":"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8","name":"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5","name":"https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5","tags":["x_refsource_MISC"]},{"url":"https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c","name":"https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c","tags":["x_refsource_MISC"]},{"url":"https://github.com/Kludex/starlette/releases/tag/0.49.1","name":"https://github.com/Kludex/starlette/releases/tag/0.49.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-407","lang":"en","description":"CWE-407: Inefficient Algorithmic Complexity","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2025-11-04T17:41:42.316Z"},"source":{"advisory":"GHSA-7f5h-v6xp-fcq8","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-10-28T20:36:34.130234Z","id":"CVE-2025-62727","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-10-28T20:36:49.189Z"}}]}}}