CVE-2021-47071

Service interruption via unreleased Hyper-V UIO buffers

Published Mar 1, 2024 · Updated May 11, 2026

Memory leak in the Hyper-V UIO driver in the Linux kernel allows local users to interrupt service through a GPADL setup failure. When vmbus_establish_gpadl() fails, the receive or send GPADL field stays unset, so hv_uio_cleanup() misses the allocated buffer. Reachability requires local low-privileged access and a Hyper-V VMBus device bound to uio_hv_generic; repeated failed setup consumes kernel memory.

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

Memory leak in the Hyper-V UIO driver in the Linux kernel allows local users to interrupt service through a GPADL setup failure. When vmbus_establish_gpadl() fails, the receive or send GPADL field stays unset, so hv_uio_cleanup() misses the allocated buffer. Reachability requires local low-privileged access and a Hyper-V VMBus device bound to uio_hv_generic; repeated failed setup consumes kernel memory.

The record

CVE
CVE-2021-47071
Published
Mar 1, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 1, 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=4.20
  2. Affected versionversion=cdfa835c6e5e87d145f9f632b58843de97509f2b <3ee098f96b8b6c1a98f7f97915f8873164e6af9d
  3. Affected versionversion=cdfa835c6e5e87d145f9f632b58843de97509f2b <53486c467e356e06aa37047c984fccd64d78c827
  4. Affected versionversion=cdfa835c6e5e87d145f9f632b58843de97509f2b <cdd91637d4ef33e2be19a8e16e72e7d00c996d76
  5. Affected versionversion=cdfa835c6e5e87d145f9f632b58843de97509f2b <d84b5e912212b05f6b5bde9f682046accfbe0354

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.20; version=cdfa835c6e5e87d145f9f632b58843de97509f2b <3ee098f96b8b6c1a98f7f97915f8873164e6af9d; version=cdfa835c6e5e87d145f9f632b58843de97509f2b <53486c467e356e06aa37047c984fccd64d78c827; version=cdfa835c6e5e87d145f9f632b58843de97509f2b <cdd91637d4ef33e2be19a8e16e72e7d00c996d76; version=cdfa835c6e5e87d145f9f632b58843de97509f2b <d84b5e912212b05f6b5bde9f682046accfbe0354

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

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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.

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Technologies

Your stack

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Your stack

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