What’s Vulnerable › Vulnerabilities

CVE-2021-20263

• Severity: low (CVSS 3.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-03-09 · updated 2026-06-17
• Weakness: CWE-281

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.

Affected products

• QEMU: from 5.0.0 before 5.2.50 — fixed in 5.2.50

How to fix

Upgrade to a fixed version: QEMU 5.2.50. Check the vendor advisory for mitigations.

References

• https://bugzilla.redhat.com/show_bug.cgi?id=1933668
• https://security.gentoo.org/glsa/202208-27
• https://security.netapp.com/advisory/ntap-20210507-0002/
• https://www.openwall.com/lists/oss-security/2021/03/08/1
• https://bugzilla.redhat.com/show_bug.cgi?id=1933668
• https://security.gentoo.org/glsa/202208-27
• https://security.netapp.com/advisory/ntap-20210507-0002/
• https://www.openwall.com/lists/oss-security/2021/03/08/1

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