[CVE-2026-63985][MODERATE 7.0] ethtool: eeprom: add more safeties to EEPROM Netlink fallback [ Upstream

[CVE-2026-63985][MODERATE 7.0] ethtool: eeprom: add more safeties to EEPROM Netlink fallback [ Upstream

[AL-KERNEL]

CVE: CVE-2026-63985
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ethtool: eeprom: add more safeties to EEPROM Netlink fallback [ Upstream
Commit: 0e182689831277faf2ef683573a60474c208f690
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0e182689831277faf2ef683573a60474c208f690
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63985
Analysis date: Sun, 19 Jul 2026 21:53:07 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: NO

Summary:
An ethtool Netlink EEPROM fallback validation bug may allow a local user to request an out-of-range EEPROM read and potentially receive uninitialized kernel heap bytes from a non-zeroed fallback buffer, with limited driver or firmware DoS risk.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-63985 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63985

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE 7.0
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-63985	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L';*CWE-20;CWE-1284;*CWE-200;CWE-908;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '6.1';DESCR 'An ethtool Netlink EEPROM fallback bug allows a local user to request a module EEPROM range where offset is valid but offset plus length exceeds the advertised EEPROM size. The fallback path can pass an out of range request to drivers or device firmware and can also expose data from a kmalloc buffer if a driver returns fewer initialized bytes than requested. For the CVSS the PR:L is used because a local user or local process is required to issue the ethtool Netlink request, while full administrator privileges are not clearly required for the get path. The issue is not directly network reachable. Impact is mainly local information disclosure and limited availability risk from driver or firmware error handling, with no clear privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	SIMPLEFIX HARDWARE LINUS  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged or low-privilege trigger: +1
  The affected path is an ethtool Netlink read path. Full administrator privileges are not clearly required from the provided patch context, but this may depend on product policy and netlink capability checks.

* Confidentiality impact plausible: +1
  The change from kmalloc() to kzalloc() suggests that a driver may return fewer initialized bytes than requested, making uninitialized kernel heap data potentially visible to userspace.

* Availability impact limited but realistic: +1
  The missing offset plus length validation may pass out-of-range EEPROM requests to drivers or device firmware, which can cause driver or firmware error behavior. The patch does not show a reliable kernel crash.

Paranoid additional signals:

* Firmware or driver mediated unsafe request handling: +1
  The malformed range can reach driver or firmware callbacks, and the commit explicitly mentions possible surprises in drivers and device FW.

* Broad practical exposure through common device-management tooling: +1
  ethtool is a common network-device management interface, although this specific EEPROM fallback path is narrower than a core packet-processing path.

Not applied:

* No remote reachable signal. This is not packet-triggered or network-triggerable.
* No generic memory corruption signal. The patch does not show UAF, OOB write, double free, type confusion, or arbitrary write.
* No privilege escalation signal. There is no demonstrated LPE primitive.
* No high-control Netlink API bonus. The user controls offset and length, but not object lifetime, callback targets, refcounts, allocator behavior, or memory layout at high granularity.

## 3. Reachability analysis

The likely trigger is a local process issuing an ethtool Netlink module EEPROM request with a valid offset but an excessive length. The exact privilege requirement should be checked against the target kernel and product policy, because some ethtool operations may be capability-gated while some read-like paths may be available to lower-privileged users.

Namespaces and containers may matter if a container or service account has access to the relevant network device and ethtool Netlink interface. This is not directly reachable from the network. Realistic exploitation requires a supported NIC or module EEPROM path using this fallback and a driver behavior where the buffer is not fully initialized or the out-of-range range reaches sensitive firmware or driver handling.

Call-site confidence: medium. The patch shows the fallback allocation and validation site, but not all driver callback behaviors.

## 4. Severity interpretation

This behaves like an actionable Moderate rather than an Important-class vulnerability. The strongest concrete issue is potential local information disclosure from an uninitialized kmalloc buffer returned through an EEPROM read fallback. The offset plus length bug also creates a driver or firmware robustness concern, but the patch does not demonstrate a kernel memory corruption primitive or reliable LPE path.

The conservative interpretation is a local info leak plus limited availability risk. The paranoid interpretation raises the score because kzalloc() strongly suggests a user-visible uninitialized-memory disclosure concern and because malformed EEPROM ranges can reach driver or firmware code.

## 5. One-sentence report phrase

An ethtool Netlink EEPROM fallback validation bug may allow a local user to request an out-of-range EEPROM read and potentially receive uninitialized kernel heap bytes from a non-zeroed fallback buffer, with limited driver or firmware DoS risk.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Manual review is recommended because the kzalloc() change is a meaningful signal for a possible uninitialized kernel memory disclosure path. This does not currently look like a strong Important candidate, but it should not be auto-closed without checking the exact ethtool capability checks and affected driver behavior.

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UPSTREAM PATCH SUMMARY
======================================================================

Patch: ethtool: eeprom: add more safeties to EEPROM Netlink fallback [ Upstream
Commit: 0e182689831277faf2ef683573a60474c208f690
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0e182689831277faf2ef683573a60474c208f690

Changed files:
  net/ethtool/eeprom.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0e182689831277faf2ef683573a60474c208f690

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-63985 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63985

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L
  The Best / paranoid CVSS score: 6.1

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: 3
  Paranoid ActionableScore: 5

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE 7.0

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).