CVE-2026-98569

A flaw was found in the Linux kernel's Generic Routing Encapsulation (GRE) subsystem. A local user with network administration privileges could cause a Denial of Service (DoS) by enabling metadata collection on an existing GRE network device through a netlink interface modification request. Because the kernel fails to verify tunnel uniqueness during link modifications, this operation can overwrite shared metadata lookup entries, breaking packet reception for other active tunnel devices in the same network namespace when either device is removed.

This vulnerability is rated as Moderate severity because exploitation requires elevated local privileges (CAP_NET_ADMIN), which restricts the attack vector and bounds the potential impact to a localized denial of service. Under default Red Hat Enterprise Linux installations, Generic Routing Encapsulation (GRE) tunnels are not configured or active. Triggering the flaw requires reconfiguring existing tunnel parameters via netlink, and the resulting disruption is confined to network traffic within the affected namespace without compromising system integrity or confidentiality.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.