CVE-2026-99251
Received Received - Intake

Infinite Loop in Linux Kernel's Hyper-V Driver

Publication date: 2026-11-03

Last updated on: 2026-11-03

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: Drivers: hv: Avoid infinite retry loop in init_vp_index() There is a retry loop in init_vp_index() where the CPUs from a certain node are stripped out if they have already been in the allocated cpumask or not in HK_TYPE_MANAGED_IRQ housekeeping cpumask. If there is no CPU left, the allocated cpumask is ignored and the process is retried again. However, if the HK_TYPE_MANAGED_IRQ housekeeping cpumask turns out not to contain any CPU in that particular node, that will become an infinite retry loop. This particular problem was reported by sashiko [1]. This should rarely happen, but we still need to guard against this. Fix this infinite loop problem by also skipping NUMA node that has no housekeeping CPU in the inner while loop of init_vp_index(). Also update the early abort check to check for the absence of online housekeeping CPUs instead of just the emptiness of the cpumask. As the outer for loop will only be reached if the housekeeping cpumask has at least one online CPU, a NUMA node with housekeeping CPUs will eventually be found.

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Meta Information

Published
2026-11-03
Last Modified
2026-11-03
Generated
2026-11-03
AI Q&A
2026-11-03
EPSS Evaluated
N/A
NVD
CVE-2026-99251
EUVD
EUVD-2026-115762

Affected Vendors & Products

Showing 7 associated CPEs
Vendor Product Version / Range
Linux Linux 6640b5df1a38801be6d0595c8cd2177d968d7ee0
Linux Linux 6640b5df1a38801be6d0595c8cd2177d968d7ee0
Linux Linux 6640b5df1a38801be6d0595c8cd2177d968d7ee0
Linux Linux 6640b5df1a38801be6d0595c8cd2177d968d7ee0
Linux Linux 6640b5df1a38801be6d0595c8cd2177d968d7ee0
Linux Linux 6640b5df1a38801be6d0595c8cd2177d968d7ee0
Linux Linux 5.19

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where an infinite retry loop occurs in the init_vp_index() function. The loop strips out CPUs from a node if they are already allocated or not in a specific housekeeping cpumask. If no CPUs remain, the loop retries indefinitely when the housekeeping cpumask lacks CPUs for that node.

Detection Guidance

This vulnerability is specific to the Linux kernel's hv drivers and involves an infinite retry loop in init_vp_index(). Detection requires checking the kernel version and examining the hv driver code for the affected logic. No direct network detection commands are applicable.

Impact Analysis

This vulnerability could cause system hangs or crashes if the infinite retry loop consumes excessive CPU resources. It may lead to unresponsive systems or denial-of-service conditions, particularly in environments using Hyper-V drivers.

Mitigation Strategies

Apply the latest kernel update that includes the fix for this issue. Monitor system logs for infinite retry loops in hv driver initialization. If affected, reboot into a patched kernel version.

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