# CVE-2026-31486: hwmon: (pmbus/core) Protect regulator operations with mutex

CVE-2026-31486 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-31486, released May 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-31486
- Priority: High
- CVSS: 7.1 (Moderate)
- EPSS: 0.0010
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 22, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-31486

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.94-1 | [DEBIAN-CVE-2026-31486](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31486.md) | May 15, 2026 |
| Linux | linux Debian 14 | 6.19.11-1 | [DEBIAN-CVE-2026-31486](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31486.md) | May 15, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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