Fluid Attacks Database

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.

Mitigation

Update Impact

Minimal update. May introduce new vulnerabilities or breaking changes.

Ecosystem	Package	Affected version	Patched versions
debian 13	starlette	=0.46.1-3 \|\| >=0 <0.46.1-3+deb13u1	0.46.1-3+deb13u1
debian 14	starlette	=0.46.1-3 \|\| >=0 <0.50.0-1	0.50.0-1
pypi	starlette	>=0.39.0 <0.49.1	0.49.1

Aliases

1. CVE-2025-627272. NVD-2025-627273. OSV-DEBIAN-2025-627274. OSV-2025-627275. GHSA-7f5h-v6xp-fcq86. GCVE-2025-627277. SECURITY-TRACKER-CVE-2025-62727

References

1. https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq82. https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c53. https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c4. https://github.com/Kludex/starlette/releases/tag/0.49.1

Does your application use this vulnerable software?

During the free trial, our tools assess your application, identify vulnerabilities, and provide recommendations for their remediation.