CVE-2026-97963

A flaw was found in the Linux kernel's stmmac network driver. An uninitialized read-write lock is accessed when configuring traffic control scheduling on an interface that has not been brought up. A local user with network administration privileges could exploit this flaw to cause a kernel crash, resulting in a Denial of Service (DoS).

A low-impact flaw was found in the Linux kernel's stmmac network driver. The driver initializes its PTP read-write lock (priv->ptp_lock) only when the network interface is opened, but the lock is also used while the interface is down and has never been opened: offloading a TAPRIO traffic-control schedule (tc_taprio_configure()) invokes the PTP gettime64() callback, and stmmac_get_time() takes the uninitialized lock. Using an uninitialized lock is undefined behavior that can lead to a kernel crash and denial of service. A local user with network administration privileges (CAP_NET_ADMIN) on a system with an affected stmmac interface could trigger this flaw; it is not triggered by packet traffic and is not network-reachable. Red Hat Enterprise Linux 6 and 7 are not affected because the vulnerable code is not present in those releases. Red Hat Enterprise Linux 8, 9, and 10, Red Hat In-Vehicle OS 2, and the RHEL CoreOS kernels shipped with OpenShift Container Platform are affected, with the fix deferred to a future planned update because of the flaw's low impact and its requirement for privileged local access; the residual risk is a local denial of service by an already-privileged user. Although the CVSS:3.1 base score for this flaw is 5.5 (Moderate), Red Hat rates its impact as Low because successful exploitation requires local CAP_NET_ADMIN privileges and affects only system availability.

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.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.