CVE-2021-47579

Local service interruption via uninstantiated OverlayFS dentry

Published Jun 19, 2024 · Updated May 11, 2026

Improper validation in Linux OverlayFS allows local users to interrupt service by mounting over an incompatible work directory. ovl_workdir_create passes a cgroup2 mkdir result to ovl_create_real even though mkdir leaves the new dentry uninstantiated, triggering a kernel warning before the filesystem is rejected. Local access and the incompatible OverlayFS work-directory setup are required, and the reported consequence is limited to availability.

CVSS severity5.5
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper validation in Linux OverlayFS allows local users to interrupt service by mounting over an incompatible work directory. ovl_workdir_create passes a cgroup2 mkdir result to ovl_create_real even though mkdir leaves the new dentry uninstantiated, triggering a kernel warning before the filesystem is rejected. Local access and the incompatible OverlayFS work-directory setup are required, and the reported consequence is limited to availability.

The record

CVE
CVE-2021-47579
Published
Jun 19, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 19, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.18
  2. Affected versionversion=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <1f5573cfe7a7056e80a92c7a037a3e69f3a13d1c
  3. Affected versionversion=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <445d2dc63e5871d218f21b8f62ab29ac72f2e6b8
  4. Affected versionversion=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <6859985a2fbda5d1586bf44538853e1be69e85f7
  5. Affected versionversion=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <d2ccdd4e4efab06178608a34d7bfb20a54104c02
  6. Affected versionversion=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <f9f300a92297be8250547347fd52216ef0177ae0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.18; version=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <1f5573cfe7a7056e80a92c7a037a3e69f3a13d1c; version=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <445d2dc63e5871d218f21b8f62ab29ac72f2e6b8; version=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <6859985a2fbda5d1586bf44538853e1be69e85f7; version=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <d2ccdd4e4efab06178608a34d7bfb20a54104c02; version=e9be9d5e76e34872f0c37d72e25bc27fe9e2c54c <f9f300a92297be8250547347fd52216ef0177ae0

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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