Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-10-18T00:00:00 kernel: thunderbolt: Hold a router reference for each allocated HopID 4.1 CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H CWE-825

In the Linux kernel, the following vulnerability has been resolved: thunderbolt: Hold a router reference for each allocated HopID tb_stop() drops the reference to all DP tunnels but does not deactivate them, thus nothing cancels a dprx_work still in flight (which holds its own tunnel reference) and the tunnel can outlive tb_switch_remove(). The HopID releases in tb_path_free() then operate on freed IDAs and trigger warnings like ida_free called for id=8 which is not allocated. This can be triggered by unbinding the driver while a DP tunnel is still waiting for the DPRX capabilities read to finish. On the Apple NHI unplugging the cable runs into just that reliably because the read can never finish right now and because the unplug powers down the entire USB4 complex and removes the NHI device. Take a router reference whenever an input or output HopID is allocated and drop it again after the HopID is released. This keeps the ports and their HopID IDAs alive for as long as they are used. The KUnit tests allocate routers without ever registering their devices so initialize the embedded struct device there as well and drop its initial reference when the test is finished.

A flaw was found in the Linux kernel's Thunderbolt driver. A physically proximate user or local attacker could trigger a Denial of Service (DoS) and crash the system by disconnecting a device or unbinding the driver while DisplayPort tunnel operations are still active. This issue occurs because the driver fails to maintain proper router reference counts during connection routing, allowing device structures to be freed prematurely while background tasks are still running. When the remaining tasks complete, cleanup operations attempt to access already freed memory, leading to memory corruption and kernel instability.

This vulnerability is rated as Moderate impact for Red Hat Enterprise Linux because exploitation requires privileged local access to unbind kernel drivers or physical access to unplug active Thunderbolt peripherals, limiting the threat scope primarily to denial of service. Systems without Thunderbolt or USB4 hardware interfaces are unaffected by default, as the corresponding driver is not engaged. In typical enterprise server deployments, restricted physical access and the lack of hot-plugged Thunderbolt displays further reduce the likelihood of real-world exploitation. Red Hat Enterprise Linux 10 Fix deferred kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Fix deferred kernel Red Hat Enterprise Linux 9 Not affected kernel-rt Red Hat OpenShift Container Platform 4 Not affected openshift/ose-rhel-coreos-8 Red Hat OpenShift Container Platform 4 Fix deferred openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 Fix deferred openshift/ose-rhel-coreos-9 https://www.cve.org/CVERecord?id=CVE-2026-98693 https://nvd.nist.gov/vuln/detail/CVE-2026-98693 https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98693.mbox