CVE-2026-98031 nexthop: Initialize extack in remove_nh_grp_entry()
A null pointer dereference in the Linux kernel nexthop module allows local attackers to cause a denial of service.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98031?
CVE-2026-98031 is a vulnerability in Linux, published on 25 Sep 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:
nexthop: Initialize extack in remove_nh_grp_entry()
remove_nh_grp_entry() prints the extack message when a listener fails to replace the reduced nexthop group. However, extack is not initialized and listeners are not required to set a message when returning an error. Neither netdevsim nor mlxsw do so when an allocation fails, resulting in the dereference of an uninitialized stack pointer.
Fix by zero-initializing extack, as was done in commit 6347c5314cee ("nexthop: initialize extack in nh_res_bucket_migrate()").
Which versions are affected by CVE-2026-98031?
How do I fix CVE-2026-98031?
Apply the vendor's patch.
Is CVE-2026-98031 being exploited?
There is no known exploitation of CVE-2026-98031 in the wild and no public exploit code.
Sources
Also known as AZL-104643, BELL-CVE-2026-98031, DEBIAN-CVE-2026-98031, GHSA-22qv-h2jq-2xcf, UBUNTU-CVE-2026-98031.