HOMEVULNERABILITIESCVE-2021-20203
LOW

CVE-2021-20203

CWE-190Published: February 25, 2021· Updated: Jun 17, 2026

3.2
CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2021-20203 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires high privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.High
User InteractionNone
ScopeChanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityLow
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:L

Affected Vendors & Products

Debian1 product(s)
debian linux
Fedora1 product(s)
fedora
qemu1 product(s)
qemu
Source: NVD CPE · 4 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://bugs.launchpad.net/qemu/+bug/1913873
PATCHhttps://bugzilla.redhat.com/show_bug.cgi?id=1922441
PATCHhttps://bugs.launchpad.net/qemu/+bug/1913873
PATCHhttps://bugzilla.redhat.com/show_bug.cgi?id=1922441
ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/04/msg00009.html
ADVISORYhttps://lists.debian.org/debian-lts-announce/2022/09/msg00008.html
ADVISORYhttps://security.gentoo.org/glsa/202208-27
ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/04/msg00009.html
ADVISORYhttps://lists.debian.org/debian-lts-announce/2022/09/msg00008.html
ADVISORYhttps://security.gentoo.org/glsa/202208-27

All References (10)

→
https://bugs.launchpad.net/qemu/+bug/1913873Exploit · Patch · Third Party Advisory
→
https://bugzilla.redhat.com/show_bug.cgi?id=1922441Issue Tracking · Patch · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2021/04/msg00009.htmlMailing List · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.htmlMailing List · Third Party Advisory
→
https://security.gentoo.org/glsa/202208-27Third Party Advisory
→
https://bugs.launchpad.net/qemu/+bug/1913873Exploit · Patch · Third Party Advisory
→
https://bugzilla.redhat.com/show_bug.cgi?id=1922441Issue Tracking · Patch · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2021/04/msg00009.htmlMailing List · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.htmlMailing List · Third Party Advisory
→
https://security.gentoo.org/glsa/202208-27Third Party Advisory

Quick Facts

CVE IDCVE-2021-20203
CVSS Score3.2 / 10
SeverityLOW
WeaknessCWE-190
CISA KEVNo
Affected3 vendor(s)
PublishedFeb 25, 2021

Related CVEs (CWE-190)

CVE-2012-5143
10.0
CVE-2015-5108
10.0
CVE-2008-2663
10.0
CVE-2012-5835
10.0
CVE-2015-5097
10.0
CVE-2013-2555
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-20203 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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