CVE-2021-47049

Kernel memory corruption via stale VMBus list entry

Published Feb 28, 2024 · Updated Aug 5, 2026

Use-after-free in Linux kernel Hyper-V VMBus code allows local users to corrupt kernel memory during channel-open error handling. The __vmbus_open function adds open_info to vmbus_connection.chn_msg_list, but its error path frees the object without first removing the list entry. Exploitation requires low-privileged local access in a Hyper-V guest and a channel-open failure; reuse of the stale entry can crash the kernel or alter kernel memory.

CVSS severity7.8
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

Use-after-free in Linux kernel Hyper-V VMBus code allows local users to corrupt kernel memory during channel-open error handling. The __vmbus_open function adds open_info to vmbus_connection.chn_msg_list, but its error path frees the object without first removing the list entry. Exploitation requires low-privileged local access in a Hyper-V guest and a channel-open failure; reuse of the stale entry can crash the kernel or alter kernel memory.

The record

CVE
CVE-2021-47049
Published
Feb 28, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 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=4.13.9 <4.14
  2. Affected versionversion=4.14
  3. Affected versionversion=6b32d45bd59982751beb8220e442b40b2706647f
  4. Affected versionversion=6f3d791f300618caf82a2be0c27456edd76d5164 <2728f289b3270b0e273292b46c534421a33bbfd5
  5. Affected versionversion=6f3d791f300618caf82a2be0c27456edd76d5164 <3e9bf43f7f7a46f21ec071cb47be92d0874c48da
  6. Affected versionversion=6f3d791f300618caf82a2be0c27456edd76d5164 <d5c7b42c9f56ca46b286daa537d181bd7f69214f
  7. Affected versionversion=6f3d791f300618caf82a2be0c27456edd76d5164 <f37dd5d1b5d38a79a4f7b8dd7bbb705505f05560

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.13.9 <4.14; version=4.14; version=6b32d45bd59982751beb8220e442b40b2706647f; version=6f3d791f300618caf82a2be0c27456edd76d5164 <2728f289b3270b0e273292b46c534421a33bbfd5; version=6f3d791f300618caf82a2be0c27456edd76d5164 <3e9bf43f7f7a46f21ec071cb47be92d0874c48da; version=6f3d791f300618caf82a2be0c27456edd76d5164 <d5c7b42c9f56ca46b286daa537d181bd7f69214f; version=6f3d791f300618caf82a2be0c27456edd76d5164 <f37dd5d1b5d38a79a4f7b8dd7bbb705505f05560

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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-416Use After Free
T1068Exploitation for Privilege Escalation

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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