CVE-2025-62727 | THREATINT

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.

PUBLISHED Reserved 2025-10-20 | Published 2025-10-28 | Updated 2025-11-04 | Assigner GitHub_M

HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-407: Inefficient Algorithmic Complexity

Product status

>= 0.39.0, < 0.49.1

affected

References

github.com/...rlette/security/advisories/GHSA-7f5h-v6xp-fcq8 exploit

github.com/...rlette/security/advisories/GHSA-7f5h-v6xp-fcq8

github.com/...ommit/4ea6e22b489ec388d6004cfbca52dd5b147127c5

github.com/...ommit/69ed26a85956ef4bd0161807eb27abf49be7cd3c

github.com/Kludex/starlette/releases/tag/0.49.1

cve.org (CVE-2025-62727)

nvd.nist.gov (CVE-2025-62727)

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