High severity7.5OSV Advisory· Published Oct 28, 2025· Updated Apr 15, 2026
CVE-2025-62727
CVE-2025-62727
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.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
starlettePyPI | >= 0.39.0, < 0.49.1 | 0.49.1 |
Affected products
1Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
6- github.com/advisories/GHSA-7f5h-v6xp-fcq8ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2025-62727ghsaADVISORY
- github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5nvdWEB
- github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3cnvdWEB
- github.com/Kludex/starlette/releases/tag/0.49.1nvdWEB
- github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8nvdWEB
News mentions
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