CVE-2026-89983 i2c: core: fix debugfs UAF on adapter removal
A race condition in the Linux kernel i2c core allows a local attacker to trigger a use-after-free, potentially causing a system crash or arbitrary code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89983?
CVE-2026-89983 is an use after free vulnerability in Linux, published on 16 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:
i2c: core: fix debugfs UAF on adapter removal
i2c_del_adapter() frees the adapter's debugfs directory before it unregisters the adapter device, but the new_device sysfs attribute stays writable until device_del(). A write racing with removal still reaches i2c_device_probe(), which passes the freed adap->debugfs to debugfs_create_dir() as the new client's parent:
BUG: KASAN: slab-use-after-free in lookup_noperm_common+0x407/0x430 Read of size 4 at addr ffff88803ef87810 by task syz.0.61/6090 lookup_noperm_common+0x407/0x430 simple_start_creating+0x9c/0x110 debugfs_start_creating+0xdb/0x1a0 debugfs_create_dir+0x24/0x350 i2c_device_probe+0x814/0xbf0
It's technically possible to create a client after i2c_deregister_clients has run. That client will never be unregistered and make wait_for_completion hang.
Close the window by removing the new_device attribute at the start of i2c_del_adapter(). device_remove_file() will drain any clients left.
Which versions are affected by CVE-2026-89983?
How do I fix CVE-2026-89983?
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-2026-89983 being exploited?
There is no known exploitation of CVE-2026-89983 in the wild and no public exploit code.
Sources
Also known as AZL-101520, BELL-CVE-2026-89983, DEBIAN-CVE-2026-89983, GHSA-xr2v-8c9q-cqgw, UBUNTU-CVE-2026-89983.