CVE-2021-47438

Service interruption via incomplete completion-queue destruction

Published May 22, 2024 · Updated Aug 5, 2026

Memory leak in the Linux kernel mlx5 Ethernet driver allows local users to interrupt service by triggering a completion-queue teardown failure. mlx5_core_destroy_cq returns immediately when queue destruction fails, leaving later cleanup operations incomplete and retaining a 64-byte debug resource object. Reachability requires a locally accessible mlx5 interface and a failed queue-destruction path; repeated triggers can exhaust kernel memory and degrade or interrupt the host.

CVSS severity7.1
High
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 the Linux kernel mlx5 Ethernet driver allows local users to interrupt service by triggering a completion-queue teardown failure. mlx5_core_destroy_cq returns immediately when queue destruction fails, leaving later cleanup operations incomplete and retaining a 64-byte debug resource object. Reachability requires a locally accessible mlx5 interface and a failed queue-destruction path; repeated triggers can exhaust kernel memory and degrade or interrupt the host.

The record

CVE
CVE-2021-47438
Published
May 22, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 22, 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

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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=3.11
  2. Affected versionversion=e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c <4f7bddf8c5c01cac74373443b13a68e1c6723a94
  3. Affected versionversion=e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c <94b960b9deffc02fc0747afc01f72cc62ab099e3
  4. Affected versionversion=e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c <ed8aafea4fec9c654e63445236e0b505e27ed3a7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.11; version=e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c <4f7bddf8c5c01cac74373443b13a68e1c6723a94; version=e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c <94b960b9deffc02fc0747afc01f72cc62ab099e3; version=e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c <ed8aafea4fec9c654e63445236e0b505e27ed3a7

Published CVSS scores

7.1kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5UbuntuCVSS: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

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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