How severe is CVE-2021-20263?

CVE-2021-20263 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-20263 being actively exploited?

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

What products are affected by CVE-2021-20263?

CVE-2021-20263 affects Qemu. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-20263?

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

When was CVE-2021-20263 published?

CVE-2021-20263 was published on 2021-03-09 and last updated on 2026-06-17.

CVE-2021-20263

CVE-2021-20263 is a low-severity vulnerability in Qemu with a CVSS 3.x base score of 3.3. 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-281.

Key facts

Severity: Low (CVSS 3.x base score 3.3)
CVSS v2: 2.1
EPSS exploit prediction: 0% (30th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-281
Affected product: Qemu
Published: 2021-03-09
Last modified: 2026-06-17

Description

A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU. The new 'xattrmap' option may cause the 'security.capability' xattr in the guest to not drop on file write, potentially leading to a modified, privileged executable in the guest. In rare circumstances, this flaw could be used by a malicious user to elevate their privileges within the guest.

Frequently asked questions

What is CVE-2021-20263?: A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU. The new 'xattrmap' option may cause the 'security.capability' xattr in the guest to not drop on file write, potentially leading to a modified, privileged executable in the guest. In rare circumstances, this flaw could be used by a malicious user to elevate their privileges within the guest.
How severe is CVE-2021-20263?: CVE-2021-20263 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-20263 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20263?: CVE-2021-20263 affects Qemu. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-20263?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-20263 published?: CVE-2021-20263 was published on 2021-03-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*

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