CVE-2026-90206 nvmet: fix max_qid race between configfs and controller allocation
A race condition in the Linux kernel nvmet subsystem allows local attackers to trigger memory corruption and potential code execution by modifying queue limits during controller allocation.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90206?
CVE-2026-90206 is a vulnerability in Linux, published on 17 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:
nvmet: fix max_qid race between configfs and controller allocation
The function nvmet_subsys_attr_qid_max_store() can race against nvmet_alloc_ctrl() when a subsystem's max_qid limit is modified.
Suppose max_qid is currently 64. If nvmet_alloc_ctrl() executes: ctrl->sqs = kzalloc_objs(struct nvmet_sq *, subsys->max_qid + 1); and at this exact point, a userspace process changes max_qid to 128, nvmet_subsys_attr_qid_max_store() will set the new max_qid value. It attempts to delete active controllers to force a reconnect, but the new controller won't be deleted because it hasn't been added to the subsys->ctrls list yet.
nvmet_alloc_ctrl() then proceeds and adds the new controller to the subsys->ctrls list. Later, when nvmet_install_queue() is called, it will see max_qid set to 128, but the memory allocated for sqs is only sized for 64 entries. This results in a KASAN out-of-bounds warning and potential memory corruptions.
Fix this by protecting the queue allocations and list insertion in nvmet_alloc_ctrl() with down_read(&nvmet_config_sem). Because nvmet_subsys_attr_qid_max_store() acquires down_write(&nvmet_config_sem) to modify the attribute, this safely prevents the configfs writer from modifying max_qid during controller creation.
Copy the max_qid from the subsystem to the controller's structure during the allocation; ctrl->max_qid never changes as long as the controller remains in LIVE state, so this will prevent similar race conditions.
Which versions are affected by CVE-2026-90206?
How do I fix CVE-2026-90206?
Apply the vendor's patch.
Is CVE-2026-90206 being exploited?
There is no known exploitation of CVE-2026-90206 in the wild and no public exploit code.
Sources
Also known as AZL-102641, BELL-CVE-2026-90206, DEBIAN-CVE-2026-90206, GHSA-6cwp-gq4q-qccv, UBUNTU-CVE-2026-90206.