High
starlette — security advisory
Starlette is a lightweight ASGI framework/toolkit. From 0.4.1 until 1.3.1, request.form() accepts max_fields and max_part_size to bound resource consumption while parsing form data. These limits are enforced for multipart/form-data, but silently ignored for application/x-www-form-urlencoded. An unauthenticated attacker can therefore send a urlencoded body with an arbitrarily large number of fields or an arbitrarily large field, even when the application configured limits it believed would apply. This vulnerability is fixed in 1.3.1.
- 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-2026-54283
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:28 UTC · Revision 1
Source evidence
Starlette is a lightweight ASGI framework/toolkit. From 0.4.1 until 1.3.1, request.form() accepts max_fields and max_part_size to bound resource consumption while parsing form data. These limits are enforced for multipart/form-data, but silently ignored for application/x-www-form-urlencoded. An unauthenticated attacker can therefore send a urlencoded body with an arbitrarily large number of fields or an arbitrarily large field, even when the application configured limits it believed would apply. This vulnerability is fixed in 1.3.1.
osv:UBUNTU-CVE-2026-54283
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": "32ab9dd9a732e35a44aac67c77e9739da00bab7e0deef3b8ea5ced6380217412",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-54283",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-54283",
"summary": "Starlette is a lightweight ASGI framework/toolkit. From 0.4.1 until 1.3.1, request.form() accepts max_fields and max_part_size to bound resource consumption while parsing form data. These limits are enforced for multipart/form-data, but silently ignored for application/x-www-form-urlencoded. An unauthenticated attacker can therefore send a urlencoded body with an arbitrarily large number of fields or an arbitrarily large field, even when the application configured limits it believed would apply. This vulnerability is fixed in 1.3.1.",
"evidence": "osv:UBUNTU-CVE-2026-54283",
"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": {
"value": "starlette",
"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": {
"value": "starlette",
"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-2026-54283",
"aliases": [
"UBUNTU-CVE-2026-54283"
],
"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/2026/UBUNTU-CVE-2026-54283.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-starlette",
"binary_version": "0.18.0-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"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/2026/UBUNTU-CVE-2026-54283.json"
},
"ecosystem_specific": {
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{
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"binary_version": "0.31.1-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
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}
]
}
],
"package": {
"name": "starlette",
"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/2026/UBUNTU-CVE-2026-54283.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-starlette",
"binary_version": "0.46.1-3"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "starlette",
"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/2026/UBUNTU-CVE-2026-54283.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/2026/UBUNTU-CVE-2026-54283.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-starlette",
"binary_version": "0.50.0-1"
}
]
}
}
],
"modified": "2026-10-17T12:58:35.447706943Z",
"provider": "osv",
"upstream": [
"CVE-2026-54283"
],
"references": [
"https://ubuntu.com/security/CVE-2026-54283",
"https://www.cve.org/CVERecord?id=CVE-2026-54283",
"https://github.com/Kludex/starlette/security/advisories/GHSA-82w8-qh3p-5jfq",
"https://github.com/Kludex/starlette/pull/3329"
]
},
"related_cves": [
{
"value": "CVE-2026-54283",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 358822,
"published_at": "2026-06-22T18:16:00+00:00"
}