CVE-2021-20263

What it is

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.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. Limited direct impact.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-03-09 18:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:33 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 3.3 LOW (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-03-09 18:15 UTC

Last modified

2026-06-17 03:33 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-281

Record status

Modified

Affected

• Qemu < 5.2.50

Attack profile CVSS 3.1 · 3.3

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-20263.md and follow it. Check whether this project is affected by CVE-2021-20263. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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