CVE-2026-89957 Linux Kernel - Logic Flaw in Hot-Unplug Handling

Linux kernel contains a logic flaw in s390/vfio-ap hot-unplug handling caused by improper bitmap_andnot() return value check, letting KVM guests retain stale hardware access to unplugged AP devices, exploit requires KVM guest with AP devices assigned.

CVSS base score 8.8 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Required
EPSS
0.18% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Logic Flaw in Hot-Unplug Handling
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Published
16 September 2026
Updated
15 October 2026

Vendor fix

Update to the latest Linux kernel version containing the fix.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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