How severe is CVE-2021-20221?

CVE-2021-20221 has a CVSS 3.x base score of 6.0, rated medium severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-20221 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20221?

CVE-2021-20221 primarily affects Redhat Enterprise Linux. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20221?

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

When was CVE-2021-20221 published?

CVE-2021-20221 was published on 2021-05-13 and last updated on 2026-06-17.

CVE-2021-20221

CVE-2021-20221 is a medium-severity vulnerability in Redhat Enterprise Linux with a CVSS 3.x base score of 6.0. 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-125.

Key facts

Severity: Medium (CVSS 3.x base score 6.0)
CVSS v2: 2.1
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Redhat Enterprise Linux
Published: 2021-05-13
Last modified: 2026-06-17

Description

An out-of-bounds heap buffer access issue was found in the ARM Generic Interrupt Controller emulator of QEMU up to and including qemu 4.2.0on aarch64 platform. The issue occurs because while writing an interrupt ID to the controller memory area, it is not masked to be 4 bits wide. It may lead to the said issue while updating controller state fields and their subsequent processing. A privileged guest user may use this flaw to crash the QEMU process on the host resulting in DoS scenario.

Frequently asked questions

What is CVE-2021-20221?: An out-of-bounds heap buffer access issue was found in the ARM Generic Interrupt Controller emulator of QEMU up to and including qemu 4.2.0on aarch64 platform. The issue occurs because while writing an interrupt ID to the controller memory area, it is not masked to be 4 bits wide. It may lead to the said issue while updating controller state fields and their subsequent processing. A privileged guest user may use this flaw to crash the QEMU process on the host resulting in DoS scenario.
How severe is CVE-2021-20221?: CVE-2021-20221 has a CVSS 3.x base score of 6.0, rated medium severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-20221 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20221?: CVE-2021-20221 primarily affects Redhat Enterprise Linux. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20221?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-20221 published?: CVE-2021-20221 was published on 2021-05-13 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:arm64:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:-:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

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