CVE-2026-64430

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Race Condition in Linux Kernel NTB EPF Driver

Publication date: 2026-07-25

Last updated on: 2026-08-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: NTB: epf: Avoid calling pci_irq_vector() from hardirq context ntb_epf_vec_isr() calls pci_irq_vector() in hardirq context to derive the vector number. pci_irq_vector() calls msi_get_virq() that takes a mutex and can therefore trigger "scheduling while atomic" splats: BUG: scheduling while atomic: kworker/u33:0/55/0x00010001 ... Call trace: ... schedule+0x38/0x110 schedule_preempt_disabled+0x28/0x50 __mutex_lock.constprop.0+0x848/0x908 __mutex_lock_slowpath+0x18/0x30 mutex_lock+0x4c/0x60 msi_domain_get_virq+0xe8/0x138 pci_irq_vector+0x2c/0x60 ntb_epf_vec_isr+0x28/0x120 [ntb_hw_epf] __handle_irq_event_percpu+0x70/0x3a8 handle_irq_event+0x48/0x100 handle_edge_irq+0x100/0x1c8 ... Cache the Linux IRQ number for vector 0 when vectors are allocated and use it as a base in the ISR. Running the ISR in a threaded IRQ handler would also avoid the problem, but that would be unnecessary here.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-07-25

Last Modified

2026-08-11

Generated

2026-08-14

AI Q&A

2026-07-25

EPSS Evaluated

2026-08-13

NVD

CVE-2026-64430

EUVD

EUVD-2026-48774

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a function called ntb_epf_vec_isr() which incorrectly calls pci_irq_vector() from a hardirq context. This leads to a scheduling while atomic bug because pci_irq_vector() uses a mutex, which is not allowed in atomic contexts. The issue causes kernel warnings and potential system instability.

Detection Guidance

This vulnerability is specific to the Linux kernel's NTB (Non-Transparent Bridge) subsystem and may trigger 'scheduling while atomic' splats in kernel logs. Check kernel logs for messages like 'BUG: scheduling while atomic' or 'mutex_lock' traces related to ntb_epf_vec_isr or pci_irq_vector.

Impact Analysis

This vulnerability can cause kernel warnings like 'scheduling while atomic' and may lead to system crashes or hangs. It affects systems using the NTB (Non-Transparent Bridge) feature with the epf driver, potentially disrupting network or peripheral device operations.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a Linux kernel issue related to interrupt handling that could cause system instability but does not involve data breaches or unauthorized access.

Mitigation Strategies

Apply the latest Linux kernel patches that resolve this issue. If you cannot patch immediately, consider disabling the affected NTB EPF driver module (ntb_hw_epf) if not in use. Monitor kernel logs for related errors as an indicator of exploitation or misconfiguration.

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