CVE-2026-31486 hwmon: (pmbus/core) Protect regulator operations with mutex
A race condition in the Linux kernel PMBus driver can cause deadlocks or instability, requiring a patch to protect regulator operations with mutexes.
- 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-2026-31486?
CVE-2026-31486 is a high-severity vulnerability in Linux kernel, published on 22 Apr 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:
hwmon: (pmbus/core) Protect regulator operations with mutex
The regulator operations pmbus_regulator_get_voltage(), pmbus_regulator_set_voltage(), and pmbus_regulator_list_voltage() access PMBus registers and shared data but were not protected by the update_lock mutex. This could lead to race conditions.
However, adding mutex protection directly to these functions causes a deadlock because pmbus_regulator_notify() (which calls regulator_notifier_call_chain()) is often called with the mutex already held (e.g., from pmbus_fault_handler()). If a regulator callback then calls one of the now-protected voltage functions, it will attempt to acquire the same mutex.
Rework pmbus_regulator_notify() to utilize a worker function to send notifications outside of the mutex protection. Events are stored as atomics in a per-page bitmask and processed by the worker.
Initialize the worker and its associated data during regulator registration, and ensure it is cancelled on device removal using devm_add_action_or_reset().
While at it, remove the unnecessary include of linux/of.h.
Which versions are affected by CVE-2026-31486?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31486?
Apply the vendor's patch.
Is CVE-2026-31486 being exploited?
There is no known exploitation of CVE-2026-31486 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-83192, BELL-CVE-2026-31486, DEBIAN-CVE-2026-31486, GHSA-rgx6-c7rp-8r4x, ROOT-OS-DEBIAN-11-CVE-2026-31486, ROOT-OS-DEBIAN-12-CVE-2026-31486 and 4 more.