CVE-2026-90284 firmware_loader: do not queue completed sysfs fallback requests
A race condition in the Linux kernel firmware loader can cause a use-after-free, leading to a system crash when a userspace helper completes a request prematurely.
- 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-2026-90284?
CVE-2026-90284 is an use after free 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:
firmware_loader: do not queue completed sysfs fallback requests
fw_load_sysfs_fallback() calls device_add() before adding the fw_priv to pending_fw_head. device_add() publishes the fallback loading interface, so a userspace helper which discovers the device by scanning sysfs can write 0 to the loading attribute and complete the request before it is queued as pending.
In that interleaving firmware_loading_store() calls fw_state_done() while pending_list still points to itself, so it cannot remove an entry from pending_fw_head. The subsequent unconditional list_add() then queues an already-completed fw_priv. Once the request is released, pending_fw_head can retain a pointer to freed memory and the next fallback request can fault while validating the list.
Only in-flight fallback requests need suspend or reboot abort handling. If the request is already DONE after device_add(), return success from the fallback path without sending another uevent, waiting again, or queueing it as pending. This preserves the invariant that pending_fw_head contains only active fallback requests.
Which versions are affected by CVE-2026-90284?
How do I fix CVE-2026-90284?
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-2026-90284 being exploited?
There is no known exploitation of CVE-2026-90284 in the wild and no public exploit code.
Sources
Also known as AZL-101912, BELL-CVE-2026-90284, DEBIAN-CVE-2026-90284, GHSA-97xh-425q-x269, UBUNTU-CVE-2026-90284.