HOMEVULNERABILITIESCVE-2021-4145
MEDIUM

CVE-2021-4145

CWE-476Published: January 25, 2022· Updated: Jun 17, 2026

6.5
CVSS v3.1

Official Description

A NULL pointer dereference issue was found in the block mirror layer of QEMU in versions prior to 6.2.0. The `self` pointer is dereferenced in mirror_wait_on_conflicts() without ensuring that it's not NULL. A malicious unprivileged user within the guest could use this flaw to crash the QEMU process on the host when writing data reaches the threshold of mirroring node.

NVD Source

Technical Analysis

CVE-2021-4145 requires local access, meaning attackers must already have a foothold on the target system.

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

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.

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.Low
User InteractionNone
ScopeChanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

Affected Vendors & Products

qemu1 product(s)
qemu
Red Hat1 product(s)
enterprise linux
Source: NVD CPE · 2 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://bugzilla.redhat.com/show_bug.cgi?id=2034602
PATCHhttps://gitlab.com/qemu-project/qemu/-/commit/66fed30c9cd11854fc878a4eceb507e915d7c9cd
PATCHhttps://bugzilla.redhat.com/show_bug.cgi?id=2034602
PATCHhttps://gitlab.com/qemu-project/qemu/-/commit/66fed30c9cd11854fc878a4eceb507e915d7c9cd
ADVISORYhttps://security.gentoo.org/glsa/202208-27
ADVISORYhttps://security.netapp.com/advisory/ntap-20220311-0004/
ADVISORYhttps://security.gentoo.org/glsa/202208-27
ADVISORYhttps://security.netapp.com/advisory/ntap-20220311-0004/

All References (8)

→
https://bugzilla.redhat.com/show_bug.cgi?id=2034602Issue Tracking · Patch · Third Party Advisory
→
https://gitlab.com/qemu-project/qemu/-/commit/66fed30c9cd11854fc878a4eceb507e915d7c9cdPatch · Third Party Advisory
→
https://security.gentoo.org/glsa/202208-27Third Party Advisory
→
https://security.netapp.com/advisory/ntap-20220311-0004/Third Party Advisory
→
https://bugzilla.redhat.com/show_bug.cgi?id=2034602Issue Tracking · Patch · Third Party Advisory
→
https://gitlab.com/qemu-project/qemu/-/commit/66fed30c9cd11854fc878a4eceb507e915d7c9cdPatch · Third Party Advisory
→
https://security.gentoo.org/glsa/202208-27Third Party Advisory
→
https://security.netapp.com/advisory/ntap-20220311-0004/Third Party Advisory

Quick Facts

CVE IDCVE-2021-4145
CVSS Score6.5 / 10
SeverityMEDIUM
WeaknessCWE-476
CISA KEVNo
Affected2 vendor(s)
PublishedJan 25, 2022

Related CVEs (CWE-476)

CVE-2010-2495
10.0
CVE-2022-36648
10.0
CVE-2020-11168
9.8
CVE-2019-20914
9.8
CVE-2018-16657
9.8
CVE-2018-1000800
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-4145 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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