CVE-2026-98569 ip_gre: Reject enabling collect metadata through changelink
A local attacker with high privileges can disrupt network metadata processing for GRE devices by improperly enabling collect metadata mode via changelink.
- 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-2026-98569?
CVE-2026-98569 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:
ip_gre: Reject enabling collect metadata through changelink
ipgre_netlink_parms() can enable collect_md on an existing GRE, GRETAP or ERSPAN device. Unlike newlink, changelink does not enforce metadata tunnel uniqueness. Converting a non-metadata device can therefore replace the metadata receive entry for another device of the same type in the same netns. Deleting either device then clears the shared entry, breaking metadata receive lookup for the surviving device.
If parameter validation fails after collect_md is set, deleting the modified device can also clear an entry it never owned.
Reject enabling metadata mode in both changelink callbacks before any encapsulation or tunnel parameters are modified. Allow requests that repeat the metadata attribute on an existing metadata device.
Which versions are affected by CVE-2026-98569?
How do I fix CVE-2026-98569?
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-2026-98569 being exploited?
There is no known exploitation of CVE-2026-98569 in the wild and no public exploit code.
Sources
Also known as AZL-109091, BELL-CVE-2026-98569, DEBIAN-CVE-2026-98569, GHSA-hr5p-wrg7-45pp, UBUNTU-CVE-2026-98569.