Low
Security advisory
An integer overflow issue was found in the vmxnet3 NIC emulator of the QEMU for versions up to v5.2.0. It may occur if a guest was to supply invalid values for rx/tx queue size or other NIC parameters. A privileged guest user may use this flaw to crash the QEMU process on the host resulting in DoS scenario.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2021-20203
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 07:04 UTC · Revision 1
Source evidence
An integer overflow issue was found in the vmxnet3 NIC emulator of the QEMU for versions up to v5.2.0. It may occur if a guest was to supply invalid values for rx/tx queue size or other NIC parameters. A privileged guest user may use this flaw to crash the QEMU process on the host resulting in DoS scenario.
osv:CVE-2021-20203
Complete source record
{
"id": "42f76869f03389d51d27eeda30bfbf89cbc43f4066aceec285da45a976f2c418",
"url": "https://osv.dev/vulnerability/CVE-2021-20203",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2021-20203",
"summary": "An integer overflow issue was found in the vmxnet3 NIC emulator of the QEMU for versions up to v5.2.0. It may occur if a guest was to supply invalid values for rx/tx queue size or other NIC parameters. A privileged guest user may use this flaw to crash the QEMU process on the host resulting in DoS scenario.",
"evidence": "osv:CVE-2021-20203",
"products": [],
"severity": "low",
"structured": {
"id": "CVE-2021-20203",
"aliases": [
"CVE-2021-20203"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:L"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/qemu/qemu",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"last_affected": "553032db17440f8de011390e5a1cfddd13751b0b"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"last_affected": "5.2.0"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"v5.2.0",
"v5.2.0-rc4",
"v5.2.0-rc3",
"v5.2.0-rc2",
"v5.2.0-rc1",
"v5.2.0-rc0",
"v5.0.0",
"v5.1.0",
"v5.1.0-rc3",
"v5.1.0-rc2",
"v5.1.0-rc1",
"v5.1.0-rc0",
"v4.2.0",
"v5.0.0-rc4",
"v5.0.0-rc3",
"v5.0.0-rc2",
"v5.0.0-rc1",
"v5.0.0-rc0",
"v4.2.0-rc5",
"v4.2.0-rc4",
"v4.2.0-rc3",
"v4.2.0-rc2",
"v4.2.0-rc1",
"v4.2.0-rc0",
"v4.1.0",
"v4.0.0",
"v4.1.0-rc5",
"v4.1.0-rc4",
"v4.1.0-rc3",
"v4.1.0-rc2",
"v4.1.0-rc1",
"v4.1.0-rc0",
"v4.0.0-rc4",
"v4.0.0-rc3",
"v4.0.0-rc2",
"v4.0.0-rc1",
"v3.1.0",
"v4.0.0-rc0",
"v3.0.0",
"v3.1.0-rc5",
"v3.1.0-rc4",
"v3.1.0-rc3",
"v3.1.0-rc2",
"v3.1.0-rc1",
"v3.1.0-rc0",
"v3.0.0-rc4",
"v3.0.0-rc3",
"v3.0.0-rc2",
"v3.0.0-rc1",
"v3.0.0-rc0",
"v2.12.0",
"v2.12.0-rc4",
"v2.12.0-rc3",
"v2.12.0-rc2",
"v2.12.0-rc1",
"v2.12.0-rc0",
"v2.11.0",
"v2.11.0-rc5",
"v2.11.0-rc4",
"v2.11.0-rc3",
"v2.11.0-rc2",
"v2.11.0-rc1",
"v2.11.0-rc0",
"v2.10.0",
"v2.10.0-rc4",
"v2.10.0-rc3",
"v2.10.0-rc2",
"v2.10.0-rc1",
"v2.9.0",
"v2.10.0-rc0",
"v2.9.0-rc5",
"v2.9.0-rc4",
"v2.9.0-rc3",
"v2.9.0-rc2",
"v2.9.0-rc1",
"v2.8.0",
"v2.9.0-rc0",
"v2.8.0-rc4",
"v2.8.0-rc3",
"v2.8.0-rc2",
"v2.8.0-rc1",
"v2.8.0-rc0",
"v2.7.0",
"v2.7.0-rc5",
"v2.7.0-rc4",
"v2.7.0-rc3",
"v2.7.0-rc2",
"v2.6.0",
"v2.7.0-rc1",
"v2.7.0-rc0",
"v2.6.0-rc5",
"v2.6.0-rc4",
"v2.6.0-rc3",
"v2.6.0-rc2",
"v2.6.0-rc1",
"v2.6.0-rc0",
"v2.5.0",
"v2.5.0-rc4",
"v2.5.0-rc3",
"v2.5.0-rc2",
"v2.5.0-rc1",
"v2.5.0-rc0",
"v2.4.0",
"v2.4.0-rc4",
"v2.4.0-rc3",
"v2.3.0",
"v2.4.0-rc2",
"v2.4.0-rc1",
"v2.4.0-rc0",
"v2.3.0-rc4",
"v2.3.0-rc3",
"v2.3.0-rc2",
"v2.3.0-rc1",
"v2.3.0-rc0",
"v2.2.0",
"v2.2.0-rc3",
"v2.2.0-rc5",
"v2.2.0-rc4",
"v2.2.0-rc2",
"v2.2.0-rc1",
"v2.2.0-rc0",
"v2.1.0",
"v2.1.0-rc5",
"v2.1.0-rc4",
"v2.1.0-rc2",
"v2.1.0-rc3",
"v2.0.0",
"v2.1.0-rc1",
"v2.1.0-rc0",
"v2.0.0-rc3",
"v2.0.0-rc2",
"v2.0.0-rc1",
"v2.0.0-rc0",
"v1.7.0",
"v1.7.0-rc2",
"v1.7.0-rc1",
"v1.7.0-rc0",
"v1.6.0",
"v1.6.0-rc3",
"v1.6.0-rc2",
"v1.6.0-rc1",
"v1.6.0-rc0",
"v1.5.0",
"v1.5.0-rc3",
"v1.5.0-rc2",
"v1.5.0-rc1",
"v1.5.0-rc0",
"v1.4.0",
"v1.4.0-rc2",
"v1.4.0-rc1",
"v1.4.0-rc0",
"v1.3.0",
"v1.3.0-rc2",
"v1.3.0-rc1",
"v1.3.0-rc0",
"v1.2.0",
"v1.2.0-rc3",
"v1.2.0-rc2",
"v1.2.0-rc1",
"v1.2.0-rc0",
"v1.1.0",
"v1.1.0-rc4",
"v1.1.0-rc3",
"v1.1.0-rc2",
"v1.1-rc2",
"v1.1-rc1",
"v1.1-rc0",
"v1.0",
"v1.0-rc4",
"v1.0-rc3",
"v1.0-rc2",
"v1.0-rc1",
"v1.0-rc0",
"v0.14.0-rc0",
"v0.13.0-rc0",
"v0.12.0-rc0",
"v0.11.0-rc0",
"v0.5.0",
"v0.4.4",
"v0.4.3",
"v0.4.2",
"v0.4.1",
"v0.4.0",
"v0.3.0",
"v0.2.0",
"v0.1.6",
"v0.1.5",
"v0.1.4",
"v0.1.3",
"v0.1.1",
"v0.1.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-20203.json"
}
},
{
"ranges": [
{
"repo": "https://gitlab.com/qemu-project/qemu",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"last_affected": "553032db17440f8de011390e5a1cfddd13751b0b"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"last_affected": "5.2.0"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"v5.2.0",
"v5.2.0-rc4",
"v5.2.0-rc3",
"v5.2.0-rc2",
"v5.2.0-rc1",
"v5.2.0-rc0",
"v5.0.0",
"v5.1.0",
"v5.1.0-rc3",
"v5.1.0-rc2",
"v5.1.0-rc1",
"v5.1.0-rc0",
"v4.2.0",
"v5.0.0-rc4",
"v5.0.0-rc3",
"v5.0.0-rc2",
"v5.0.0-rc1",
"v5.0.0-rc0",
"v4.2.0-rc5",
"v4.2.0-rc4",
"v4.2.0-rc3",
"v4.2.0-rc2",
"v4.2.0-rc1",
"v4.2.0-rc0",
"v4.1.0",
"v4.0.0",
"v4.1.0-rc5",
"v4.1.0-rc4",
"v4.1.0-rc3",
"v4.1.0-rc2",
"v4.1.0-rc1",
"v4.1.0-rc0",
"v4.0.0-rc4",
"v4.0.0-rc3",
"v4.0.0-rc2",
"v4.0.0-rc1",
"v3.1.0",
"v4.0.0-rc0",
"v3.0.0",
"v3.1.0-rc5",
"v3.1.0-rc4",
"v3.1.0-rc3",
"v3.1.0-rc2",
"v3.1.0-rc1",
"v3.1.0-rc0",
"v3.0.0-rc4",
"v3.0.0-rc3",
"v3.0.0-rc2",
"v3.0.0-rc1",
"v3.0.0-rc0",
"v2.12.0",
"v2.12.0-rc4",
"v2.12.0-rc3",
"v2.12.0-rc2",
"v2.12.0-rc1",
"v2.12.0-rc0",
"v2.11.0",
"v2.11.0-rc5",
"v2.11.0-rc4",
"v2.11.0-rc3",
"v2.11.0-rc2",
"v2.11.0-rc1",
"v2.11.0-rc0",
"v2.10.0",
"v2.10.0-rc4",
"v2.10.0-rc3",
"v2.10.0-rc2",
"v2.10.0-rc1",
"v2.9.0",
"v2.10.0-rc0",
"v2.9.0-rc5",
"v2.9.0-rc4",
"v2.9.0-rc3",
"v2.9.0-rc2",
"v2.9.0-rc1",
"v2.8.0",
"v2.9.0-rc0",
"v2.8.0-rc4",
"v2.8.0-rc3",
"v2.8.0-rc2",
"v2.8.0-rc1",
"v2.8.0-rc0",
"v2.7.0",
"v2.7.0-rc5",
"v2.7.0-rc4",
"v2.7.0-rc3",
"v2.7.0-rc2",
"v2.6.0",
"v2.7.0-rc1",
"v2.7.0-rc0",
"v2.6.0-rc5",
"v2.6.0-rc4",
"v2.6.0-rc3",
"v2.6.0-rc2",
"v2.6.0-rc1",
"v2.6.0-rc0",
"v2.5.0",
"v2.5.0-rc4",
"v2.5.0-rc3",
"v2.5.0-rc2",
"v2.5.0-rc1",
"v2.5.0-rc0",
"v2.4.0",
"v2.4.0-rc4",
"v2.4.0-rc3",
"v2.3.0",
"v2.4.0-rc2",
"v2.4.0-rc1",
"v2.4.0-rc0",
"v2.3.0-rc4",
"v2.3.0-rc3",
"v2.3.0-rc2",
"v2.3.0-rc1",
"v2.3.0-rc0",
"v2.2.0",
"v2.2.0-rc3",
"v2.2.0-rc5",
"v2.2.0-rc4",
"v2.2.0-rc2",
"v2.2.0-rc1",
"v2.2.0-rc0",
"v2.1.0",
"v2.1.0-rc5",
"v2.1.0-rc4",
"v2.1.0-rc2",
"v2.1.0-rc3",
"v2.0.0",
"v2.1.0-rc1",
"v2.1.0-rc0",
"v2.0.0-rc3",
"v2.0.0-rc2",
"v2.0.0-rc1",
"v2.0.0-rc0",
"v1.7.0",
"v1.7.0-rc2",
"v1.7.0-rc1",
"v1.7.0-rc0",
"v1.6.0",
"v1.6.0-rc3",
"v1.6.0-rc2",
"v1.6.0-rc1",
"v1.6.0-rc0",
"v1.5.0",
"v1.5.0-rc3",
"v1.5.0-rc2",
"v1.5.0-rc1",
"v1.5.0-rc0",
"v1.4.0",
"v1.4.0-rc2",
"v1.4.0-rc1",
"v1.4.0-rc0",
"v1.3.0",
"v1.3.0-rc2",
"v1.3.0-rc1",
"v1.3.0-rc0",
"v1.2.0",
"v1.2.0-rc3",
"v1.2.0-rc2",
"v1.2.0-rc1",
"v1.2.0-rc0",
"v1.1.0",
"v1.1.0-rc4",
"v1.1.0-rc3",
"v1.1.0-rc2",
"v1.1-rc2",
"v1.1-rc1",
"v1.1-rc0",
"v1.0",
"v1.0-rc4",
"v1.0-rc3",
"v1.0-rc2",
"v1.0-rc1",
"v1.0-rc0",
"v0.14.0-rc0",
"v0.13.0-rc0",
"v0.12.0-rc0",
"v0.11.0-rc0",
"v0.5.0",
"v0.4.4",
"v0.4.3",
"v0.4.2",
"v0.4.1",
"v0.4.0",
"v0.3.0",
"v0.2.0",
"v0.1.6",
"v0.1.5",
"v0.1.4",
"v0.1.3",
"v0.1.1",
"v0.1.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-20203.json"
}
}
],
"modified": "2026-10-24T10:30:48.251668349Z",
"provider": "osv",
"references": [
"https://lists.debian.org/debian-lts-announce/2021/04/msg00009.html",
"https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html",
"https://security.gentoo.org/glsa/202208-27",
"https://bugs.launchpad.net/qemu/+bug/1913873",
"https://bugzilla.redhat.com/show_bug.cgi?id=1922441"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*",
"cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*"
],
"vendor_product": "debian:debian_linux",
"extracted_events": [
{
"range": [
{
"introduced": "9.0"
},
{
"last_affected": "9.0"
},
{
"introduced": "10.0"
},
{
"last_affected": "10.0"
}
],
"source": "CPE_STRING"
}
]
},
{
"cpes": [
"cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*"
],
"vendor_product": "fedoraproject:fedora",
"extracted_events": [
{
"range": [
{
"introduced": "33"
},
{
"last_affected": "33"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2021-20203",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 436723,
"published_at": "2021-02-25T20:15:11.597+00:00"
}