CVE-2025-39876

Kernel crash via unchecked PHY-device lookup

Published Sep 23, 2025 · Updated Sep 23, 2025

NULL pointer dereference in the Linux FEC Ethernet driver allows local users to crash the kernel during PHY reset after clock enable. fec_enet_phy_reset_after_clk_enable() accepts a NULL result from of_phy_find_device() and dereferences phy_dev without checking it. The path requires local low-privileged access and an affected FEC/PHY device configuration; triggering it interrupts the host through a kernel crash.

CVSS severity5.5
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux FEC Ethernet driver allows local users to crash the kernel during PHY reset after clock enable. fec_enet_phy_reset_after_clk_enable() accepts a NULL result from of_phy_find_device() and dereferences phy_dev without checking it. The path requires local low-privileged access and an affected FEC/PHY device configuration; triggering it interrupts the host through a kernel crash.

The record

CVE
CVE-2025-39876
Published
Sep 23, 2025
Updated
Sep 23, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 23, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.10
  2. Affected versionversion=64a632da538a6827fad0ea461925cedb9899ebe2 <03e79de4608bdd48ad6eec272e196124cefaf798
  3. Affected versionversion=64a632da538a6827fad0ea461925cedb9899ebe2 <4fe53aaa4271a72fe5fe3e88a45ce01646b68dc5
  4. Affected versionversion=64a632da538a6827fad0ea461925cedb9899ebe2 <5f1bb554a131e59b28482abad21f691390651752
  5. Affected versionversion=64a632da538a6827fad0ea461925cedb9899ebe2 <eb148d85e126c47d65be34f2a465d69432ca5541
  6. Affected versionversion=64a632da538a6827fad0ea461925cedb9899ebe2 <fe78891f296ac05bf4e5295c9829ef822f3c32e7
  7. Affected versionversion=8a6ab151443cd71e2aa5e8b7014e3453dbd51935
  8. Affected versionversion=9e70485b40c8306298adea8bdc867ca27f88955a
  9. Affected versionversion=c068e505f229ca5f778f825f1401817ce818e917
  10. Affected versionversion=ce88b5f42868ef4964c497d4dfcd25e88fd60c5b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.10; version=64a632da538a6827fad0ea461925cedb9899ebe2 <03e79de4608bdd48ad6eec272e196124cefaf798; version=64a632da538a6827fad0ea461925cedb9899ebe2 <4fe53aaa4271a72fe5fe3e88a45ce01646b68dc5; version=64a632da538a6827fad0ea461925cedb9899ebe2 <5f1bb554a131e59b28482abad21f691390651752; version=64a632da538a6827fad0ea461925cedb9899ebe2 <eb148d85e126c47d65be34f2a465d69432ca5541; version=64a632da538a6827fad0ea461925cedb9899ebe2 <fe78891f296ac05bf4e5295c9829ef822f3c32e7; version=8a6ab151443cd71e2aa5e8b7014e3453dbd51935; version=9e70485b40c8306298adea8bdc867ca27f88955a; version=c068e505f229ca5f778f825f1401817ce818e917; version=ce88b5f42868ef4964c497d4dfcd25e88fd60c5b

Published CVSS scores

5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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