CVE-2023-53205

Host crash via racy physical CPU lookup

Published Sep 15, 2025 · Updated Sep 15, 2025

Race condition in Linux KVM on s390 allows guest OS users to crash the host through concurrent DIAGNOSE 0x9c requests. The __diag_time_slice_end_directed function rereads tcpu->cpu after validating it, so concurrent vCPU descheduling can change the value to -1 before lowcore_ptr and pcpu_devices are indexed. A multi-vCPU guest and enabled DIAGNOSE 0x9c forwarding are required; winning the race can dereference invalid host-kernel array entries and cause an oops or panic.

CVSS severity7.3
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Race condition in Linux KVM on s390 allows guest OS users to crash the host through concurrent DIAGNOSE 0x9c requests. The __diag_time_slice_end_directed function rereads tcpu->cpu after validating it, so concurrent vCPU descheduling can change the value to -1 before lowcore_ptr and pcpu_devices are indexed. A multi-vCPU guest and enabled DIAGNOSE 0x9c forwarding are required; winning the race can dereference invalid host-kernel array entries and cause an oops or panic.

The record

CVE
CVE-2023-53205
Published
Sep 15, 2025
Updated
Sep 15, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-787, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 2025Record 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=5.13
  2. Affected versionversion=87e28a15c42cc592009c32a8c20e5789059027c2 <0bc380beb78aa352eadbc21d934dd9606fcee808
  3. Affected versionversion=87e28a15c42cc592009c32a8c20e5789059027c2 <86bfb18bad60fc468e5f112cbbd918462a8dd435
  4. Affected versionversion=87e28a15c42cc592009c32a8c20e5789059027c2 <a9ccf140a2a03a0ae82be4bdfbdd17bdaea72ff5
  5. Affected versionversion=87e28a15c42cc592009c32a8c20e5789059027c2 <dc7e0192c470a53d847c79a2796f9ac429477a26

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.13; version=87e28a15c42cc592009c32a8c20e5789059027c2 <0bc380beb78aa352eadbc21d934dd9606fcee808; version=87e28a15c42cc592009c32a8c20e5789059027c2 <86bfb18bad60fc468e5f112cbbd918462a8dd435; version=87e28a15c42cc592009c32a8c20e5789059027c2 <a9ccf140a2a03a0ae82be4bdfbdd17bdaea72ff5; version=87e28a15c42cc592009c32a8c20e5789059027c2 <dc7e0192c470a53d847c79a2796f9ac429477a26

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.3Linux kernel CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/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.

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

CWE-787Out-of-bounds Write
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo