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CVE Record

CVE-2025-39876: net: fec: Fix possible NPD in fec_enet_phy_reset_after_clk_enable()

In the Linux kernel, the following vulnerability has been resolved: net: fec: Fix possible NPD in fec_enet_phy_reset_after_clk_enable() The function of_phy_find_device may return NULL, so we need to take care before dereferencing phy_dev.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2025-39876 is a Linux kernel bug in the fec network driver. A missing NULL check could make the kernel dereference a missing PHY device object, causing a crash or unreliable networking. The sources do not provide CVSS, confirmed exploitation, or a broad product impact statement.

Executive priority

Handle through normal kernel patch governance, with higher priority for network-dependent appliances or embedded systems. There is no cited exploitation, no CVSS score, and no evidence of data compromise, but a kernel crash can still create business-impacting downtime.

Technical view

The kernel fix adds handling for of_phy_find_device returning NULL before fec_enet_phy_reset_after_clk_enable dereferences phy_dev. This is a null pointer dereference in net/fec path logic. Published affected-version data is kernel-oriented and should be reconciled with each distribution’s backports.

Likely exposure

Exposure appears limited to Linux systems running affected kernels where the fec driver and relevant PHY reset path are used. This is most important for appliances, embedded Linux, and servers whose network interface depends on that driver, but the source bundle does not enumerate vendors or hardware models.

Exploitation context

The source bundle does not report active exploitation, and CISA KEV status is false. Triggerability is not fully described in the provided sources, so treat it as a stability and availability risk until vendor advisories clarify attack requirements.

Researcher notes

Key uncertainty is trigger context. The record names a NULL pointer dereference fix but does not describe a remote, local, or physical attack path. Validate affectedness through source-level backport checks, not version strings alone, because distribution kernels may carry fixes independently.

Mitigation direction

  • Update to a kernel or distribution package containing the referenced stable fixes.
  • Check Debian LTS guidance if using Debian-supported kernels.
  • Confirm your vendor’s advisory before assuming a downstream kernel is affected or fixed.
  • Prioritize systems where fec-backed networking is required for availability.
  • Regression test networking after applying kernel updates.

Validation and detection

  • Inventory kernel versions and identify systems using the fec network driver.
  • Compare installed kernels against CVE and distribution advisory affected-status data.
  • Confirm the relevant stable fix is present or backported by the vendor.
  • Review boot and kernel logs for fec PHY initialization failures.
  • Test link bring-up and network availability after remediation.
Prepared
Confidence
medium
Sources
11

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2025-39876 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
1ADP providers
10Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux9e70485b40c8306298adea8bdc867ca27f88955a, 64a632da538a6827fad0ea461925cedb9899ebe2, 64a632da538a6827fad0ea461925cedb9899ebe2, 64a632da538a6827fad0ea461925cedb9899ebe2, 64a632da538a6827fad0ea461925cedb9899ebe2, 64a632da538a6827fad0ea461925cedb9899ebe2, 64a632da538a6827fad0ea461925cedb9899ebe2, 64a632da538a6827fad0ea461925cedb9899ebe2, c068e505f229ca5f778f825f1401817ce818e917, 8a6ab151443cd71e2aa5e8b7014e3453dbd51935, ce88b5f42868ef4964c497d4dfcd25e88fd60c5b, 5.4.73, 4.19.153, 5.8.17, 5.9.2unaffected
LinuxLinux5.10, 0, 5.4.300, 5.10.245, 5.15.194, 6.1.153, 6.6.107, 6.12.48, 6.16.8, 6.17affected
Weakness

CWE details

No CWE listed

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