CVE-2026-98688 thunderbolt: Fix NULL dereference in tb_remove_work()
A race condition in the Linux kernel Thunderbolt driver causes a NULL pointer dereference, leading to a system crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98688?
CVE-2026-98688 is a vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
thunderbolt: Fix NULL dereference in tb_remove_work()
There is a slight race between tb_remove_work() and tb_domain_remove() which leads to dereferencing a NULL tb->root_switch pointer inside tb_free_unplugged_xdomains():
Thread A Thread B
tb_remove_work() tb_domain_remove() mutex_lock(&tb->lock) tb_stop() /* doesn't cancel a running callback */ cancel_delayed_work(&tcm->remove_work) ... tb_switch_remove(tb->root_switch) tb->root_switch = NULL mutex_unlock(&tb->lock) mutex_lock(&tb->lock) ... /* without checking ->root_switch */ tb_free_unplugged_xdomains(tb->root_switch) mutex_unlock(&tb->lock)
Commit a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") doesn't seem right to move tb_free_unplugged_xdomains() out of the &tb->lock section and the check for tb->root_switch, in particular. It states:
For this reason separate removing the XDomain from the topology data structures (where we need the lock) from unregistering the device from the bus (where remove callbacks of the drivers are being called).
tb_free_unplugged_xdomains() belongs to the former group of functions requiring the lock. And it also calls tb_xdomain_remove() which should only be called with &tb->lock held.
Found by Linux Verification Center (linuxtesting.org) with Svace static analysis tool.
Which versions are affected by CVE-2026-98688?
How do I fix CVE-2026-98688?
Apply the vendor's patch.
Is CVE-2026-98688 being exploited?
There is no known exploitation of CVE-2026-98688 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-98688, GHSA-g38j-2fmx-j974, UBUNTU-CVE-2026-98688.