CVE-2026-90311 thermal: hwmon: Remove hwmon class device along with its parent
A use-after-free vulnerability in the Linux kernel thermal subsystem allows local attackers to cause a denial of service by triggering improper device removal.
- 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-2026-90311?
CVE-2026-90311 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:
thermal: hwmon: Remove hwmon class device along with its parent
The current code creates one hwmon device per thermal zone type and that device is registered under the first thermal zone of the given type.
That turns out to be problematic when the thermal zone holding the hwmon device is removed.
For example, say that there are two ACPI thermal zones on a system
/sys/devices/virtual/thermal/thermal_zone0/ /sys/devices/virtual/thermal/thermal_zone1/
The current code registers a hwmon class device for thermal_zone0 only:
/sys/devices/virtual/thermal/thermal_zone0/hwmon0/
because the type is "acpitz" for both of them, but it adds a sysfs attribute that belongs to thermal_zone1 under it:
/sys/devices/virtual/thermal/thermal_zone0/hwmon0/temp2_input
There is also
/sys/devices/virtual/thermal/thermal_zone0/hwmon0/temp1_input
which belongs to thermal_zone0.
When thermal_zone0 is removed, say because the ACPI thermal driver is unbound from the underlying platform device, thermal_remove_hwmon_sysfs() skips the removal of hwmon0 because of the temp2_input attribute belonging to thermal_zone1 which effectively prevents thermal_zone0 removal from making progress.
Address this by making thermal_remove_hwmon_sysfs() remove the entire hwmon class device interface for the given thermal zone type when the thermal zone device holding it is removed.
To prevent races with thermal_add_hwmon_sysfs() that may interfere with this, carry out the entire addition and removal of hwmon sysfs interfaces for thermal zones under thermal_hwmon_list_lock.
Also adjust the layout of the labels in thermal_add_hwmon_sysfs() to the current kernel coding style to align with the new "unlock" label.
Which versions are affected by CVE-2026-90311?
How do I fix CVE-2026-90311?
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-2026-90311 being exploited?
There is no known exploitation of CVE-2026-90311 in the wild and no public exploit code.
Sources
Also known as AZL-102362, BELL-CVE-2026-90311, DEBIAN-CVE-2026-90311, GHSA-43gv-wm7g-h6q4, UBUNTU-CVE-2026-90311.