CVE-2021-47011

Local system crash via resurrected memcg reference

Published Feb 28, 2024 · Updated Aug 5, 2026

Use-after-free in affected Linux kernel versions allows local users to crash the system through memory-cgroup operations. The memcontrol uncharge path calls css_get after a memory-cgroup reference count reaches zero, allowing a freed memcg reference to be reacquired. A local user needs permission to create and remove memory cgroups and migrate processes; successful exploitation interrupts the system.

CVSS severity5.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Use-after-free in affected Linux kernel versions allows local users to crash the system through memory-cgroup operations. The memcontrol uncharge path calls css_get after a memory-cgroup reference count reaches zero, allowing a freed memcg reference to be reacquired. A local user needs permission to create and remove memory cgroups and migrate processes; successful exploitation interrupts the system.

The record

CVE
CVE-2021-47011
Published
Feb 28, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=26f54dac15640c65ec69867e182de7be708ea389 <31df8bc4d3feca9f9c6b2cd06fd64a111ae1a0e6
  2. Affected versionversion=3de7d4f25a7438f09fef4e71ef111f1805cd8e7c <89b1ed358e01e1b0417f5d3b0082359a23355552
  3. Affected versionversion=3de7d4f25a7438f09fef4e71ef111f1805cd8e7c <9f38f03ae8d5f57371b71aa6b4275765b65454fd
  4. Affected versionversion=3de7d4f25a7438f09fef4e71ef111f1805cd8e7c <c3ae6a3f3ca4f02f6ccddf213c027302586580d0
  5. Affected versionversion=5.10.11 <5.10.37
  6. Affected versionversion=5.11

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=26f54dac15640c65ec69867e182de7be708ea389 <31df8bc4d3feca9f9c6b2cd06fd64a111ae1a0e6; version=3de7d4f25a7438f09fef4e71ef111f1805cd8e7c <89b1ed358e01e1b0417f5d3b0082359a23355552; version=3de7d4f25a7438f09fef4e71ef111f1805cd8e7c <9f38f03ae8d5f57371b71aa6b4275765b65454fd; version=3de7d4f25a7438f09fef4e71ef111f1805cd8e7c <c3ae6a3f3ca4f02f6ccddf213c027302586580d0; version=5.10.11 <5.10.37; version=5.11

Published CVSS scores

5.5NVDCVSS: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

T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo