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CVE-2025-62727

HIGH

7.5

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.

CVE Details

CVSS v3.1 Score7.5

SeverityHIGH

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

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionNONE

Published10/28/2025

Last Modified11/4/2025

Sourcenvd

Honeypot Sightings0

Weaknesses (CWE)

CWE-407

References

https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5(security-advisories@github.com)

https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c(security-advisories@github.com)

https://github.com/Kludex/starlette/releases/tag/0.49.1(security-advisories@github.com)

https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8(security-advisories@github.com)

https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8(134c704f-9b21-4f2e-91b3-4a467353bcc0)

IOC Correlations

No correlations recorded

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