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CVE Record

CVE-2025-38110: net/mdiobus: Fix potential out-of-bounds clause 45 read/write access

In the Linux kernel, the following vulnerability has been resolved: net/mdiobus: Fix potential out-of-bounds clause 45 read/write access When using publicly available tools like 'mdio-tools' to read/write data from/to network interface and its PHY via C45 (clause 45) mdiobus, there is no verification of parameters passed to the ioctl and it accepts any mdio address. Currently there is support for 32 addresses in kernel via PHY_MAX_ADDR define, but it is possible to pass higher value than that via ioctl. While read/write operation should generally fail in this case, mdiobus provides stats array, where wrong address may allow out-of-bounds read/write. Fix that by adding address verification before C45 read/write operation. While this excludes this access from any statistics, it improves security of read/write operation.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A local user with limited privileges may abuse Linux network PHY management requests to access memory outside an internal statistics array. Successful exploitation could compromise confidentiality, integrity, or availability. The flaw is not remotely reachable under the supplied CVSS assessment, but it matters on shared, appliance, and locally accessible Linux systems.

Executive priority

Prioritize patching shared Linux hosts, network appliances, and systems where less-trusted users or services have local access. Internet exposure alone does not establish reachability. Treat remediation as high priority where MDIO access is available; otherwise schedule it through normal kernel maintenance after validating distribution exposure.

Technical view

Clause 45 MDIO ioctl handling accepted PHY addresses beyond the kernel-supported 32-address range. Although the underlying operation would normally fail, the invalid address could index beyond the mdiobus statistics array, causing out-of-bounds reads or writes. The kernel fix validates the address before Clause 45 operations.

Likely exposure

Exposure requires an affected Linux kernel and local, low-privileged access capable of issuing Clause 45 MDIO requests against a network interface and PHY. The source identifies affected releases including 6.3, 6.6.94, 6.12.34, 6.15.3, and 6.16, but distribution-specific backports require separate confirmation.

Exploitation context

The supplied CVSS score is 7.8 with local access, low complexity, low privileges, and no user interaction. CISA KEV status is false, and the supplied sources provide no evidence of active exploitation or a public exploit. Public MDIO tooling is mentioned as a way to reach the vulnerable interface, not as evidence of exploitation.

Researcher notes

The security boundary failure is missing address validation before Clause 45 read/write processing. Values above PHY_MAX_ADDR can affect indexing of mdiobus statistics storage even when hardware access fails. The fix adds validation but excludes rejected accesses from statistics. Exact vulnerable and fixed package boundaries should be derived from distribution advisories or commit backports.

Mitigation direction

  • Install a distribution kernel containing the upstream address-validation fix.
  • Confirm remediation against the relevant stable-kernel commit or distribution advisory.
  • Until patched, restrict untrusted local access to MDIO-capable interfaces and tooling.
  • Check vendor guidance for supported fixed packages and required reboot procedures.

Validation and detection

  • Inventory kernel versions on systems exposing physical network interfaces and PHY management.
  • Check distribution changelogs for CVE-2025-38110 or the referenced stable-kernel fixes.
  • Verify the running kernel after patching, including completion of any required reboot.
  • Confirm Clause 45 requests reject PHY addresses outside the supported 0–31 range.
  • Review which local users or services can access MDIO management interfaces.
Prepared
Confidence
high
Sources
6

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

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CVE-2025-38110 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

1CVSS vectors
3Timeline events
0ADP providers
5Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-38110Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4e4aafcddbbfcdd6eed5780e190fcbfac8b4685a, 4e4aafcddbbfcdd6eed5780e190fcbfac8b4685a, 4e4aafcddbbfcdd6eed5780e190fcbfac8b4685a, 4e4aafcddbbfcdd6eed5780e190fcbfac8b4685aunaffected
LinuxLinux6.3, 0, 6.6.94, 6.12.34, 6.15.3, 6.16affected
Weakness

CWE details

No CWE listed

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