What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-09-15 · updated 2026-10-15
• Weakness: CWE-787

Description

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.

Affected products

• Linux kernel: from 5.13 before 5.15.121; from 5.16 before 6.1.39; from 6.2 before 6.4.4 — fixed in 5.15.121, 6.1.39, 6.4.4

How to fix

Upgrade to a fixed version: Linux kernel 5.15.121, 6.1.39, 6.4.4. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0bc380beb78aa352eadbc21d934dd9606fcee808
• https://git.kernel.org/stable/c/86bfb18bad60fc468e5f112cbbd918462a8dd435
• https://git.kernel.org/stable/c/a9ccf140a2a03a0ae82be4bdfbdd17bdaea72ff5
• https://git.kernel.org/stable/c/dc7e0192c470a53d847c79a2796f9ac429477a26

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