SB20261029123 - Race condition in Linux kernel x86 kernel

Description

This security bulletin contains information about 1 vulnerability.

1) Race condition (CVE-ID: CVE-2026-99178)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to cause a denial of service by triggering a kernel panic in a KVM guest.

The vulnerability exists due to a race condition in the Linux kernel's x86 KVM asynchronous page-fault handler when a kernel-mode page fault in NMI context consumes pending asynchronous page-fault reason flags belonging to an interrupted handler. A local user can run perf sampling with user call chains and an invalid user-space frame pointer to trigger a guest kernel panic if the sampling NMI faults during the interval between asynchronous page-fault delivery and consumption of its reason flags.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/81d99abe2bd81379abfb595e403bbbee6fbfc624
• https://git.kernel.org/stable/c/b77e9622bbade9812e2090c66d25c372f515e921
• https://git.kernel.org/stable/c/f45ee1ff6358a22d7e22a4c53cb3148ea97b10d9