Skip to content
Fencer Vulns
high 7.0

CVE-2025-39905 json

net: phylink: add lock for serializing concurrent pl->phydev writes with resolver

published 2025-10-01 13 mo ago modified 2026-10-19 20 d ago also EUVD-2025-32887

cvss
7.0
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 1%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

net: phylink: add lock for serializing concurrent pl->phydev writes with resolver

Currently phylink_resolve() protects itself against concurrent phylink_bringup_phy() or phylink_disconnect_phy() calls which modify pl->phydev by relying on pl->state_mutex.

The problem is that in phylink_resolve(), pl->state_mutex is in a lock inversion state with pl->phydev->lock. So pl->phydev->lock needs to be acquired prior to pl->state_mutex. But that requires dereferencing pl->phydev in the first place, and without pl->state_mutex, that is racy.

Hence the reason for the extra lock. Currently it is redundant, but it will serve a functional purpose once mutex_lock(&phy->lock) will be moved outside of the mutex_lock(&pl->state_mutex) section.

Another alternative considered would have been to let phylink_resolve() acquire the rtnl_mutex, which is also held when phylink_bringup_phy() and phylink_disconnect_phy() are called. But since phylink_disconnect_phy() runs under rtnl_lock(), it would deadlock with phylink_resolve() when calling flush_work(&pl->resolve). Additionally, it would have been undesirable because it would have unnecessarily blocked many other call paths as well in the entire kernel, so the smaller-scoped lock was preferred.

Patch / fix

  • Linux Linux 6.16.8, 6.17
  • linux Debian 14 6.16.8-1

debian advisories DEBIAN-CVE-2025-39905

  • kernel RHEL 10.1 6.12.0-124.27.1.el10_1
  • rv RHEL 10.1 6.12.0-124.27.1.el10_1
  • perf RHEL 10.1 6.12.0-124.27.1.el10_1
  • rtla RHEL 10.1 6.12.0-124.27.1.el10_1
  • libperf RHEL 10.1 6.12.0-124.27.1.el10_1
  • kernel-rt RHEL 10.1 6.12.0-124.27.1.el10_1
  • kernel-64k RHEL 10.1 6.12.0-124.27.1.el10_1
  • kernel-core RHEL 10.1 6.12.0-124.27.1.el10_1

red hat advisories RHSA-2026:0453

  • kernel-abi-stablelists AlmaLinux 10 6.12.0-124.27.1.el10_1

almalinux advisories ALSA-2026:0453

  • kernel Rocky Linux 10 6.12.0-124.27.1.el10_1

rocky linux advisories RLSA-2026:0453

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-2025-39905 updated cvss 6.5

kernel: net: phylink: add lock for serializing concurrent pl->phydev writes with resolver

  • Red Hat Enterprise Linux 8 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +6 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-selftests-internal
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-124.27.1.el10_1, perf 6.12.0-124.27.1.el10_1, rtla 6.12.0-124.27.1.el10_1, python3-perf 6.12.0-124.27.1.el10_1, kernel-devel-matched 6.12.0-124.27.1.el10_1, kernel-64k-devel-matched 6.12.0-124.27.1.el10_1, +7 more Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-124.27.1.el10_1, kernel-64k 6.12.0-124.27.1.el10_1, kernel-core 6.12.0-124.27.1.el10_1, kernel-tools 6.12.0-124.27.1.el10_1, kernel-modules 6.12.0-124.27.1.el10_1, kernel-64k-core 6.12.0-124.27.1.el10_1, +28 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-124.27.1.el10_1, kernel-debuginfo-common-s390x 6.12.0-124.27.1.el10_1, kernel-debuginfo-common-x86_64 6.12.0-124.27.1.el10_1, kernel-debuginfo-common-aarch64 6.12.0-124.27.1.el10_1, kernel-debuginfo-common-ppc64le 6.12.0-124.27.1.el10_1 Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-124.27.1.el10_1, kernel-rt-64k 6.12.0-124.27.1.el10_1, kernel-rt-core 6.12.0-124.27.1.el10_1, kernel-rt-modules 6.12.0-124.27.1.el10_1, kernel-rt-64k-core 6.12.0-124.27.1.el10_1, kernel-rt-debug-core 6.12.0-124.27.1.el10_1, +14 more Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-124.27.1.el10_1, kernel-rt-core 6.12.0-124.27.1.el10_1, kernel-rt-modules 6.12.0-124.27.1.el10_1, kernel-rt-debug-core 6.12.0-124.27.1.el10_1, kernel-rt-modules-core 6.12.0-124.27.1.el10_1, kernel-rt-debug-modules 6.12.0-124.27.1.el10_1, +4 more
    fixed: vendor fix RHSA-2026:0453
  • 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 Enterprise Linux 8 perf, kernel, bpftool, kernel-core, kernel-tools, python3-perf, +17 more
    not affected: component not present
  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 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
total
Assessed
9 mo ago

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
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.