CVE-2023-52639

Host crash via uninitialized shadow-map ownership

Published Apr 3, 2024 · Updated May 11, 2026

Race condition in the Linux kernel's KVM s390 VSIE subsystem allows local users to crash the host kernel during shadow creation. The acquire_gmap_shadow function assigns gmap->private only after publishing the new shadow map, so kvm_s390_vsie_gmap_notifier can dereference a zero owner; the fix makes child maps inherit the parent's private field at creation. Exploitation requires low-privileged local access to an s390 KVM host and winning the shadow-creation race, and the documented consequence is a host-kernel crash.

CVSS severity4.7
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in the Linux kernel's KVM s390 VSIE subsystem allows local users to crash the host kernel during shadow creation. The acquire_gmap_shadow function assigns gmap->private only after publishing the new shadow map, so kvm_s390_vsie_gmap_notifier can dereference a zero owner; the fix makes child maps inherit the parent's private field at creation. Exploitation requires low-privileged local access to an s390 KVM host and winning the shadow-creation race, and the documented consequence is a host-kernel crash.

The record

CVE
CVE-2023-52639
Published
Apr 3, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-362, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 3, 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=4.8
  2. Affected versionversion=a3508fbe9dc6dd3bece0c7bf889cc085a011738c <28bb27824f25f36e5f80229a358d66ee09244082
  3. Affected versionversion=a3508fbe9dc6dd3bece0c7bf889cc085a011738c <5df3b81a567eb565029563f26f374ae3803a1dfc
  4. Affected versionversion=a3508fbe9dc6dd3bece0c7bf889cc085a011738c <f5572c0323cf8b4f1f0618178648a25b8fb8a380
  5. Affected versionversion=a3508fbe9dc6dd3bece0c7bf889cc085a011738c <fe752331d4b361d43cfd0b89534b4b2176057c32

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.8; version=a3508fbe9dc6dd3bece0c7bf889cc085a011738c <28bb27824f25f36e5f80229a358d66ee09244082; version=a3508fbe9dc6dd3bece0c7bf889cc085a011738c <5df3b81a567eb565029563f26f374ae3803a1dfc; version=a3508fbe9dc6dd3bece0c7bf889cc085a011738c <f5572c0323cf8b4f1f0618178648a25b8fb8a380; version=a3508fbe9dc6dd3bece0c7bf889cc085a011738c <fe752331d4b361d43cfd0b89534b4b2176057c32

Published CVSS scores

4.7NIST NVDCVSS:3.1/AV:L/AC:H/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-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1499Endpoint Denial of Service

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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