CVE-2026-98585 eth: fbnic: Avoid rounding zero ring sizes
A local attacker can cause a denial of service in the fbnic network driver by triggering undefined behavior with zero ring sizes.
- 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-2026-98585?
CVE-2026-98585 is a denial of service vulnerability in Linux, published on 18 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:
eth: fbnic: Avoid rounding zero ring sizes
roundup_pow_of_two() is undefined for zero. ethtool permits a zero ring size to reach the driver, where the minimum-size check should reject it.
Leave zero unchanged while rounding nonzero ring sizes. The minimum-size check then rejects zero deterministically without changing the established behavior for other values.
Which versions are affected by CVE-2026-98585?
How do I fix CVE-2026-98585?
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-2026-98585 being exploited?
There is no known exploitation of CVE-2026-98585 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98585, DEBIAN-CVE-2026-98585, GHSA-pmrp-mw94-3ww9, UBUNTU-CVE-2026-98585.