CVE-2026-74656

A flaw was found in the Linux kernel's IPv4 networking stack. A use-after-free vulnerability exists in the fib_nhc_update_mtu() function due to a race condition during nexthop exception table updates. This allows for a scenario where memory can be freed while still being accessed, which can lead to a system crash, resulting in a Denial of Service (DoS).

This vulnerability is rated as Moderate impact because successful exploitation requires winning a timing-sensitive race condition during concurrent route adjustments, with the primary risk confined to a local denial of service via a kernel crash. In standard Red Hat Enterprise Linux environments, IPv4 routing and path MTU discovery operate by default, but triggering interface MTU changes typically requires elevated privileges such as CAP_NET_ADMIN. Consequently, unprivileged local users face substantial barriers in orchestrating the necessary concurrent state changes to destabilize the host.

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.