CVE-2026-98693
Received Received - Intake

Thunderbolt HopID Use-After-Free in Linux Kernel

Publication date: 2026-10-18

Last updated on: 2026-10-18

Assigner: kernel.org

Description
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.

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Meta Information

Published
2026-10-18
Last Modified
2026-10-18
Generated
2026-10-18
AI Q&A
2026-10-18
EPSS Evaluated
N/A
NVD
CVE-2026-98693
EUVD
EUVD-2026-103947

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
Linux Linux d6d458d42e1e1544a18f37f1d5c840e00d5261b9
Linux Linux d6d458d42e1e1544a18f37f1d5c840e00d5261b9
Linux Linux d6d458d42e1e1544a18f37f1d5c840e00d5261b9
Linux Linux 6.14

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves improper handling of HopIDs in Thunderbolt drivers. When a driver is unbound while a DisplayPort tunnel is still active, the system fails to properly deactivate the tunnel, leading to a use-after-free scenario where HopID releases operate on freed memory. This triggers warnings like 'ida_free called for id=8 which is not allocated' and can cause system instability.

Impact Analysis

This vulnerability may cause system crashes or warnings when unplugging Thunderbolt devices, particularly on Apple hardware where it can reliably trigger due to hardware behavior. It could lead to memory corruption or instability in the Linux kernel, affecting system reliability.

Mitigation Strategies

Update the Linux kernel to the latest patched version to resolve the thunderbolt driver issue. Avoid unbinding the thunderbolt driver while DP tunnels are active to prevent triggering the vulnerability.

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