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CVE Record

CVE-2023-53205: KVM: s390/diag: fix racy access of physical cpu number in diag 9c handler

In the Linux kernel, the following vulnerability has been resolved: KVM: s390/diag: fix racy access of physical cpu number in diag 9c handler We do check for target CPU == -1, but this might change at the time we are going to use it. Hold the physical target CPU in a local variable to avoid out-of-bound accesses to the cpu arrays.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2023-53205 is a Linux kernel KVM issue in the s390 diagnostic 9c handler. A racing CPU-number check could let the kernel use a changed value and read or write outside CPU arrays. Business impact depends on whether affected Linux kernels are used on s390 KVM virtualization hosts.

Executive priority

Do not treat this as broadly urgent without s390 KVM exposure. For organizations running s390 virtualization, schedule kernel patching through the normal security update process and prioritize shared or tenant-facing hosts.

Technical view

The fix stores the physical target CPU in a local variable after checking for -1, preventing a time-of-check/time-of-use race before indexing CPU arrays. The affected area is Linux KVM s390 diag handling. The source bundle provides no CVSS, CWE, exploitability detail, or impact classification beyond out-of-bound array access risk.

Likely exposure

Likely limited to Linux systems using KVM on s390/s390x where the affected kernel code is present. Organizations without IBM Z or LinuxONE-style s390 virtualization exposure are unlikely to be affected, based on the component named in the sources.

Exploitation context

The bundle does not show active exploitation, public exploit code, or KEV listing. Exploitation preconditions are not fully described. Treat this as a kernel virtualization bug requiring exposure validation before assigning urgency.

Researcher notes

Evidence is limited to the CVE record and Linux stable commits. The vulnerability is a race around target CPU validation in KVM s390 diag 9c handling. No CVSS, CWE, proof of exploitation, or precise attack path is provided in the bundle.

Mitigation direction

  • Identify s390/s390x Linux KVM hosts and their running kernel versions.
  • Apply vendor kernel updates containing the referenced stable fixes.
  • If no packaged fix is available, monitor Linux vendor guidance for CVE-2023-53205.
  • Prioritize hosts running untrusted or multi-tenant virtual machines.

Validation and detection

  • Check whether any production host uses Linux KVM on s390/s390x.
  • Compare kernel packages against vendor advisories for CVE-2023-53205.
  • Confirm the relevant stable fix commit is included in deployed kernels.
  • Document systems where s390 KVM is not present as not exposed.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2023-53205 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
5Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux87e28a15c42cc592009c32a8c20e5789059027c2, 87e28a15c42cc592009c32a8c20e5789059027c2, 87e28a15c42cc592009c32a8c20e5789059027c2, 87e28a15c42cc592009c32a8c20e5789059027c2unaffected
LinuxLinux5.13, 0, 5.15.121, 6.1.39, 6.4.4, 6.5affected
Weakness

CWE details

No CWE listed

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