How severe is CVE-2021-4145?

CVE-2021-4145 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-4145 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-4145?

CVE-2021-4145 primarily affects Redhat Enterprise Linux. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-4145?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-4145 published?

CVE-2021-4145 was published on 2022-01-25 and last updated on 2026-06-17.

CVE-2021-4145

CVE-2021-4145 is a medium-severity vulnerability in Redhat Enterprise Linux with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.9
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Redhat Enterprise Linux
Published: 2022-01-25
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-4145?: 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.
How severe is CVE-2021-4145?: CVE-2021-4145 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-4145 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-4145?: CVE-2021-4145 primarily affects Redhat Enterprise Linux. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-4145?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-4145 published?: CVE-2021-4145 was published on 2022-01-25 and last updated on 2026-06-17.

References

Affected products (7)

cpe:2.3:a:qemu:qemu:6.1.0:-:*:*:*:*:*:*
cpe:2.3:a:qemu:qemu:6.1.0:rc0:*:*:*:*:*:*
cpe:2.3:a:qemu:qemu:6.1.0:rc1:*:*:*:*:*:*
cpe:2.3:a:qemu:qemu:6.1.0:rc2:*:*:*:*:*:*
cpe:2.3:a:qemu:qemu:6.1.0:rc3:*:*:*:*:*:*
cpe:2.3:a:qemu:qemu:6.1.0:rc4:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:-:*:*:*

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