CVE-2026-98018 net: mctp: i3c: serialize probe with bus removal
A race condition in the Linux kernel MCTP I3C driver allows use-after-free, potentially leading to code execution or denial of service.
- 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-2026-98018?
CVE-2026-98018 is an use after free vulnerability in Linux, published on 25 Sep 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:
net: mctp: i3c: serialize probe with bus removal
mctp_i3c_probe() drops busdevs_lock after finding the matching bus. A concurrent I3C_NOTIFY_BUS_REMOVE can then unregister and free the bus netdev before probe passes its private data to mctp_i3c_add_device(). The latter consequently adds a list node through a freed mbus pointer.
Keep busdevs_lock held until the device has been added. This also satisfies the __must_hold annotation on mctp_i3c_add_device().
Which versions are affected by CVE-2026-98018?
How do I fix CVE-2026-98018?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-98018 being exploited?
There is no known exploitation of CVE-2026-98018 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98018, DEBIAN-CVE-2026-98018, GHSA-wc27-x2j9-p8cq, UBUNTU-CVE-2026-98018.