CVE-2026-64430 NTB: epf: Avoid calling pci_irq_vector() from hardirq context
A bug in the Linux kernel NTB endpoint driver causes a system crash when handling interrupts, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64430?
CVE-2026-64430 is a high-severity denial of service vulnerability in Linux kernel, published on 25 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-64430?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64430?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-64430 being exploited?
There is no known exploitation of CVE-2026-64430 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64430, DEBIAN-CVE-2026-64430, GHSA-wwc2-fvch-vwhh, ROOT-OS-DEBIAN-12-CVE-2026-64430, ROOT-OS-UBUNTU-2204-CVE-2026-64430, UBUNTU-CVE-2026-64430.