CVE-2021-47070

Kernel memory consumption via probe error leak

Published Mar 1, 2024 · Updated May 11, 2026

Memory leak in Linux allows local users to consume kernel memory by forcing an error during uio_hv_generic device probing. The probe allocates a VMBus ring with vmbus_alloc_ring(), but its error path omits vmbus_free_ring(), leaving that allocation unreleased. The driver must be loaded and manually bound to a Hyper-V VMBus device; each reachable failing probe consumes kernel memory, while further impact is not published.

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 allows local users to consume kernel memory by forcing an error during uio_hv_generic device probing. The probe allocates a VMBus ring with vmbus_alloc_ring(), but its error path omits vmbus_free_ring(), leaving that allocation unreleased. The driver must be loaded and manually bound to a Hyper-V VMBus device; each reachable failing probe consumes kernel memory, while further impact is not published.

The record

CVE
CVE-2021-47070
Published
Mar 1, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
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

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=4.20
  2. Affected versionversion=cdfa835c6e5e87d145f9f632b58843de97509f2b <0b0226be3a52dadd965644bc52a807961c2c26df
  3. Affected versionversion=cdfa835c6e5e87d145f9f632b58843de97509f2b <261bbd90cc53d2835343f056770156cf1e82cf03
  4. Affected versionversion=cdfa835c6e5e87d145f9f632b58843de97509f2b <5f59240cf25b2f7a0fdffc2701482a70310fec07

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.20; version=cdfa835c6e5e87d145f9f632b58843de97509f2b <0b0226be3a52dadd965644bc52a807961c2c26df; version=cdfa835c6e5e87d145f9f632b58843de97509f2b <261bbd90cc53d2835343f056770156cf1e82cf03; version=cdfa835c6e5e87d145f9f632b58843de97509f2b <5f59240cf25b2f7a0fdffc2701482a70310fec07

Published CVSS scores

5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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

No sourced classifications are available.

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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