CVE-2026-98262 ata: libahci: clear PxCLBU and PxFBU for AHCI_HFLAG_32BIT_ONLY
A kernel bug causes system boot failure on specific hardware when 32-bit DMA is forced, requiring a patch to clear specific AHCI registers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98262?
CVE-2026-98262 is a denial of service vulnerability in Linux, published on 6 Oct 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:
ata: libahci: clear PxCLBU and PxFBU for AHCI_HFLAG_32BIT_ONLY
A user reported that commit 105c42566a55 ("ata: ahci: force 32-bit DMA for JMicron JMB582/JMB585") made the JMicron JMB585 unusable on his board.
The failure is seen as soon as the ahci driver is probed, and booting with iommu=off does not solve the problem.
Looking at the AHCI specification, PxCLBU and PxFBU are both read only '0' for HBAs that do not support 64-bit addressing.
For HBAs that do support 64-bit addressing, the registers are read write, with a reset value that is Implementation Specific.
When using the AHCI_HFLAG_32BIT_ONLY flag, the HBA does support 64-bit addressing, and a 32-bit DMA mask is set by simply clearing HOST_CAP_64. Thus, in this case, we need to explicitly clear the registers to 0.
Which versions are affected by CVE-2026-98262?
How do I fix CVE-2026-98262?
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-2026-98262 being exploited?
There is no known exploitation of CVE-2026-98262 in the wild and no public exploit code.
Sources
Also known as AZL-106389, BELL-CVE-2026-98262, DEBIAN-CVE-2026-98262, GHSA-599j-5783-gx62, UBUNTU-CVE-2026-98262.