High
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
- 0.14.1-1, 0.16.0-1, 0.18.0-1, 0.30.0-1, 0.31.1-1, 0.46.1-2, 0.46.1-3, 0.50.0-1, 1.1.0-1, 1.3.1-1, 1.7.0-2
- Fixed versions
- Not specified
- CVEs
- CVE-2025-62727
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 01:48 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:UBUNTU-CVE-2025-62727
starlette
Fixed versions: Not specified
starlette
Fixed versions: Not specified
starlette
Fixed versions: Not specified
starlette
Fixed versions: Not specified
starlette
Fixed versions: Not specified
Complete source record
{
"id": "13bcd2625edc7b3d25416dd442461b7fad4302d1ebe6de3c4776f787d38c0707",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2025-62727",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-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:UBUNTU-CVE-2025-62727",
"products": [
{
"name": {
"value": "starlette",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.14.1-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.16.0-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.18.0-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "starlette",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.30.0-1",
"evidence": "/affected/1/versions"
},
{
"value": "0.31.1-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
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"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.46.1-2",
"evidence": "/affected/2/versions"
},
{
"value": "0.46.1-3",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
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"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.50.0-1",
"evidence": "/affected/3/versions"
},
{
"value": "1.1.0-1",
"evidence": "/affected/3/versions"
},
{
"value": "1.3.1-1",
"evidence": "/affected/3/versions"
},
{
"value": "1.7.0-2",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "starlette",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.46.1-3",
"evidence": "/affected/4/versions"
},
{
"value": "0.50.0-1",
"evidence": "/affected/4/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2025-62727",
"aliases": [
"UBUNTU-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"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "starlette",
"purl": "pkg:deb/ubuntu/starlette?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"0.14.1-1",
"0.16.0-1",
"0.18.0-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-62727.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-starlette",
"binary_version": "0.18.0-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
}
],
"package": {
"name": "starlette",
"purl": "pkg:deb/ubuntu/starlette?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"0.30.0-1",
"0.31.1-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-62727.json"
},
"ecosystem_specific": {
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{
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],
"package": {
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"purl": "pkg:deb/ubuntu/starlette?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"0.46.1-2",
"0.46.1-3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-62727.json"
},
"ecosystem_specific": {
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{
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}
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}
},
{
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"type": "ECOSYSTEM",
"events": [
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"introduced": "0"
}
]
}
],
"package": {
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"purl": "pkg:deb/ubuntu/starlette?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"0.50.0-1",
"1.1.0-1",
"1.3.1-1",
"1.7.0-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-62727.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-starlette",
"binary_version": "1.7.0-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "starlette",
"purl": "pkg:deb/ubuntu/starlette?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"0.46.1-3",
"0.50.0-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-62727.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-starlette",
"binary_version": "0.50.0-1"
}
]
}
}
],
"modified": "2026-10-17T12:57:28.757442456Z",
"provider": "osv",
"upstream": [
"CVE-2025-62727"
],
"references": [
"https://ubuntu.com/security/CVE-2025-62727",
"https://www.cve.org/CVERecord?id=CVE-2025-62727",
"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8",
"https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5"
]
},
"related_cves": [
{
"value": "CVE-2025-62727",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 357567,
"published_at": "2025-10-28T21:15:00+00:00"
}