CVE-2026-64254 NTB: epf: Avoid pci_iounmap() with offset when PEER_SPAD and CONFIG share BAR
A kernel warning triggered by improper memory unmapping in the NTB endpoint function driver can lead to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64254?
CVE-2026-64254 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
NTB: epf: Avoid pci_iounmap() with offset when PEER_SPAD and CONFIG share BAR
When BAR_PEER_SPAD and BAR_CONFIG share one PCI BAR, the module teardown path ends up calling pci_iounmap() on the same iomem with some offset, which is unnecessary and triggers a kernel warning like the following:
Trying to vunmap() nonexistent vm area (0000000069a5ffe8) WARNING: mm/vmalloc.c:3470 at vunmap+0x58/0x68, CPU#5: modprobe/2937 [...] Call trace: vunmap+0x58/0x68 (P) iounmap+0x34/0x48 pci_iounmap+0x2c/0x40 ntb_epf_pci_remove+0x44/0x80 [ntb_hw_epf] pci_device_remove+0x48/0xf8 device_remove+0x50/0x88 device_release_driver_internal+0x1c8/0x228 driver_detach+0x50/0xb0 bus_remove_driver+0x74/0x100 driver_unregister+0x34/0x68 pci_unregister_driver+0x34/0xa0 ntb_epf_pci_driver_exit+0x14/0xfe0 [ntb_hw_epf] [...]
Fix it by unmapping only when PEER_SPAD and CONFIG use difference bars.
Weakness: CWE-617
Which versions are affected by CVE-2026-64254?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64254?
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-2026-64254 being exploited?
There is no known exploitation of CVE-2026-64254 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64254, DEBIAN-CVE-2026-64254, GHSA-c496-vr74-8pgf, ROOT-OS-UBUNTU-2204-CVE-2026-64254, UBUNTU-CVE-2026-64254.