CVE-2021-47214

Local service interruption via HugeTLB reservation leak

Published Apr 10, 2024 · Updated May 23, 2026

A resource leak in Linux 5.13.13 through 5.15.4 allows local users to exhaust HugeTLB reservations through userfaultfd operations. In hugetlb_mcopy_atomic_pte(), UFFDIO_CONTINUE error exits misclassify a cached page and call restore_reserve_on_error(), corrupting reservation accounting. Local low-privilege access and a userfaultfd-managed hugetlbfs mapping are required; repeated failures consume reservations and interrupt memory-dependent services.

CVSS severity5.5
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A resource leak in Linux 5.13.13 through 5.15.4 allows local users to exhaust HugeTLB reservations through userfaultfd operations. In hugetlb_mcopy_atomic_pte(), UFFDIO_CONTINUE error exits misclassify a cached page and call restore_reserve_on_error(), corrupting reservation accounting. Local low-privilege access and a userfaultfd-managed hugetlbfs mapping are required; repeated failures consume reservations and interrupt memory-dependent services.

The record

CVE
CVE-2021-47214
Published
Apr 10, 2024
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 10, 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=5.13.13 <5.14
  2. Affected versionversion=5.14
  3. Affected versionversion=515b6124df6a84c957c5cc6bb6e8309dae7b1e9c
  4. Affected versionversion=c7b1850dfb41d0b4154aca8dbc04777fbd75616f <b5069d44e2fbc4a9093d005b3ef0949add3dd27e
  5. Affected versionversion=c7b1850dfb41d0b4154aca8dbc04777fbd75616f <cc30042df6fcc82ea18acf0dace831503e60a0b7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.13.13 <5.14; version=5.14; version=515b6124df6a84c957c5cc6bb6e8309dae7b1e9c; version=c7b1850dfb41d0b4154aca8dbc04777fbd75616f <b5069d44e2fbc4a9093d005b3ef0949add3dd27e; version=c7b1850dfb41d0b4154aca8dbc04777fbd75616f <cc30042df6fcc82ea18acf0dace831503e60a0b7

Published CVSS scores

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

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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
T1499.004Application or System Exploitation Flood

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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