starlette — security advisory
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.
- Products
- starlette
- Affected versions
- 0.46.1-3
- Fixed versions
- 0.46.1-3+deb13u1, 0.50.0-1
- CVEs
- CVE-2025-62727
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 28 Oct 2026, 11:06 UTC · Revision 1
Source evidence
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.
osv:DEBIAN-CVE-2025-62727
starlette
Fixed versions: 0.46.1-3+deb13u1
starlette
Fixed versions: 0.50.0-1
Complete source record
{
"id": "7bd900270fb3be22dd1bb5e7f2734e2e48d151bb4df678ebc690c676c350dc4d",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2025-62727",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2025-62727",
"summary": "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.",
"evidence": "osv:DEBIAN-CVE-2025-62727",
"products": [
{
"name": {
"value": "starlette",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "0.46.1-3+deb13u1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "0.46.1-3",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "starlette",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "0.50.0-1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": [
{
"value": "0.46.1-3",
"evidence": "/affected/1/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "DEBIAN-CVE-2025-62727",
"aliases": [
"DEBIAN-CVE-2025-62727"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.46.1-3+deb13u1"
}
]
}
],
"package": {
"name": "starlette",
"purl": "pkg:deb/debian/starlette?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"0.46.1-3"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-62727.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.50.0-1"
}
]
}
],
"package": {
"name": "starlette",
"purl": "pkg:deb/debian/starlette?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"0.46.1-3"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-62727.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-09T09:47:24.031480346Z",
"provider": "osv",
"upstream": [
"CVE-2025-62727"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2025-62727"
]
},
"related_cves": [
{
"value": "CVE-2025-62727",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 111450,
"published_at": "2025-10-28T21:15:40.447+00:00"
}