{"cve":"CVE-2025-62727","nvd":{"published":"2025-10-28T21:15:40.447","modified":"2026-10-08T11:10:00.250","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-407"],"references":["https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5","https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c","https://github.com/Kludex/starlette/releases/tag/0.49.1","https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8","https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:14:53.307938015+00:00"},"epss":{"cve":"CVE-2025-62727","score":0.008,"percentile":0.56295,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-7f5h-v6xp-fcq8","url":"https://osv.dev/vulnerability/GHSA-7f5h-v6xp-fcq8","summary":"Starlette vulnerable to O(n^2) DoS via Range header merging in ``starlette.responses.FileResponse``","modified":"2026-09-10T03:50:29.490992457Z","packages":[{"ecosystem":"PyPI","name":"starlette","purl":"pkg:pypi/starlette","ranges":[">=0.39.0 <0.49.1"],"fixed":["0.49.1"]}]},{"id":"PYSEC-2026-1942","url":"https://osv.dev/vulnerability/PYSEC-2026-1942","summary":"Starlette vulnerable to O(n^2) DoS via Range header merging in ``starlette.responses.FileResponse``","modified":"2026-07-07T17:47:58.859983831Z","packages":[{"ecosystem":"PyPI","name":"starlette","purl":"pkg:pypi/starlette","ranges":[">=0.39.0 <0.49.1"],"fixed":["0.49.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}