CVE-2021-47116

Service interruption via skipped initialization cleanup

Published Mar 15, 2024 · Updated May 23, 2026

Memory leak in Linux ext4 initialization allows local users to exhaust kernel memory by initializing a corrupted filesystem image. ext4_mb_init_backend takes the err_freesgi branch when s_log_groups_per_flex is at least 32, bypassing cleanup of the buddy-cache inode and previously allocated group information. Reaching the leak requires local ability to initialize the malformed filesystem; repeated triggers can deplete memory and interrupt service.

CVSS severity5.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in Linux ext4 initialization allows local users to exhaust kernel memory by initializing a corrupted filesystem image. ext4_mb_init_backend takes the err_freesgi branch when s_log_groups_per_flex is at least 32, bypassing cleanup of the buddy-cache inode and previously allocated group information. Reaching the leak requires local ability to initialize the malformed filesystem; repeated triggers can deplete memory and interrupt service.

The record

CVE
CVE-2021-47116
Published
Mar 15, 2024
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 15, 2024CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=5.10.27 <5.10.43
  2. Affected versionversion=5.11.11 <5.12
  3. Affected versionversion=5.12
  4. Affected versionversion=9e7af67e9521fb5cbb5b01aca22921c313c2e48e
  5. Affected versionversion=df61d3cff422433527d3bc388f69484f0781d226 <2050c6e5b161e5e25ce3c420fef58b24fa388a49
  6. Affected versionversion=f91436d55a279f045987e8b8c1385585dca54be9 <04fb2baa0b147f51db065a1b13a11954abe592d0
  7. Affected versionversion=f91436d55a279f045987e8b8c1385585dca54be9 <a8867f4e3809050571c98de7a2d465aff5e4daf5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.10.27 <5.10.43; version=5.11.11 <5.12; version=5.12; version=9e7af67e9521fb5cbb5b01aca22921c313c2e48e; version=df61d3cff422433527d3bc388f69484f0781d226 <2050c6e5b161e5e25ce3c420fef58b24fa388a49; version=f91436d55a279f045987e8b8c1385585dca54be9 <04fb2baa0b147f51db065a1b13a11954abe592d0; version=f91436d55a279f045987e8b8c1385585dca54be9 <a8867f4e3809050571c98de7a2d465aff5e4daf5

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.

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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

CWE-401Missing Release of Memory after Effective Lifetime

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

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Your stack

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