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Fencer Vulns
high 7.1

CVE-2026-31486 json

hwmon: (pmbus/core) Protect regulator operations with mutex

published 2026-04-22 6 mo ago modified 2026-10-30 9 d ago also EUVD-2026-24852

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 0%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 6.1.191, 6.6.143, 6.12.92, 6.18.21, 6.19.11, 7.0
  • linux Debian 13 6.12.94-1
  • linux Debian 14 6.19.11-1

debian advisories DEBIAN-CVE-2026-31486

  • linux Ubuntu 24.04 LTS 6.8.0-139.139
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1064.67
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1067.75
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1062.70
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1064.65
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1067.75
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1049.53
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1064.68

ubuntu advisories UBUNTU-CVE-2026-31486

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel Azure Linux 3.0 6.6.143.1-1

azure linux advisories AZL-83192

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-31486 updated cvss 5.5

kernel: hwmon: (pmbus/core) Protect regulator operations with mutex

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
23 d ago

Exploit prediction

0.10% chance of exploitation in the next 30 days, higher than 0% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
  • CWE-667 Improper Locking
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.