CVE-2021-47341

Host disruption via duplicate KVM device destruction

Published May 21, 2024 · Updated Aug 5, 2026

Use-after-free in Linux KVM coalesced MMIO allows local users to read freed kernel memory and crash the host through VM ioctls. When bus unregistration returns an error, kvm_io_bus_unregister_dev() already destroys the target, but the caller invokes its destructor again and dereferences the freed device. Access to a KVM VM file descriptor and a registered coalesced-MMIO zone is required; the demonstrated consequence is an invalid kernel-memory read detected by KASAN.

CVSS severity7.8
High
EPSS probability0.25%
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 KVM coalesced MMIO allows local users to read freed kernel memory and crash the host through VM ioctls. When bus unregistration returns an error, kvm_io_bus_unregister_dev() already destroys the target, but the caller invokes its destructor again and dereferences the freed device. Access to a KVM VM file descriptor and a registered coalesced-MMIO zone is required; the demonstrated consequence is an invalid kernel-memory read detected by KASAN.

The record

CVE
CVE-2021-47341
Published
May 21, 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. May 21, 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=168e82f640ed1891a700bdb43e37da354b2ab63c
  2. Affected versionversion=2a20592baff59c5351c5200ec667e1a2aa22af85 <679837dc0abaa2c6e2a7bcd86483e05eee1d5066
  3. Affected versionversion=50cbad42bfea8c052b7ca590bd4126cdc898713c <8d7c539316d652d217e5e82b89ee204c812a7061
  4. Affected versionversion=5.10.37 <5.10.52
  5. Affected versionversion=5.11.21 <5.12
  6. Affected versionversion=5.12.4 <5.12.19
  7. Affected versionversion=5.13
  8. Affected versionversion=5.4.119 <5.4.134
  9. Affected versionversion=5d3c4c79384af06e3c8e25b7770b6247496b4417 <069d44a24c0ff8f85adf49233aae7a8ca16f5c7e
  10. Affected versionversion=5d3c4c79384af06e3c8e25b7770b6247496b4417 <23fa2e46a5556f787ce2ea1a315d3ab93cced204
  11. Affected versionversion=7d1bc32d6477ff96a32695ea4be8144e4513ab2d <f2ff9d03432fcb160e9f7d4be26174d89de2779a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=168e82f640ed1891a700bdb43e37da354b2ab63c; version=2a20592baff59c5351c5200ec667e1a2aa22af85 <679837dc0abaa2c6e2a7bcd86483e05eee1d5066; version=50cbad42bfea8c052b7ca590bd4126cdc898713c <8d7c539316d652d217e5e82b89ee204c812a7061; version=5.10.37 <5.10.52; version=5.11.21 <5.12; version=5.12.4 <5.12.19; version=5.13; version=5.4.119 <5.4.134; version=5d3c4c79384af06e3c8e25b7770b6247496b4417 <069d44a24c0ff8f85adf49233aae7a8ca16f5c7e; version=5d3c4c79384af06e3c8e25b7770b6247496b4417 <23fa2e46a5556f787ce2ea1a315d3ab93cced204; version=7d1bc32d6477ff96a32695ea4be8144e4513ab2d <f2ff9d03432fcb160e9f7d4be26174d89de2779a

Published CVSS scores

7.8kernel.orgCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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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