[CVE-2026-80676][MODERATE 7.0] Drivers: hv: vmbus: use generic driver_override infrastructure [ Upstream

[CVE-2026-80676][MODERATE 7.0] Drivers: hv: vmbus: use generic driver_override infrastructure [ Upstream

[AL-KERNEL]

CVE: CVE-2026-80676
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Drivers: hv: vmbus: use generic driver_override infrastructure [ Upstream
Commit: d1cb12ae81d2f7a58b0b1cfb51862afca98e6058
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d1cb12ae81d2f7a58b0b1cfb51862afca98e6058
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80676
Analysis date: Fri, 28 Aug 2026 05:30:20 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-80676 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80676

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: YES

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

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-80676	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'A race in the Hyper V vmbus driver_override handling can cause a use after free because the bus match callback may read driver_override without the device lock while another path replaces or frees the same string through sysfs. The vulnerable access occurs during driver probing through __driver_attach, where match() is intentionally called without the device lock, so concurrent override updates can leave vmbus_match using stale memory. For the CVSS the PR:L is used for the paranoid score because practical exposure may include delegated device management, service accounts, container root, or reduced capability root rather than only full host administrator access. The issue is local and is not directly network reachable. Impact is at least local denial of service via kernel crash. In worst case it may allow limited confidentiality or integrity impact due to kernel use after free behavior, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	LOCK UAF HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=5
ActionableScoreLower=4

1. ActionableScore
* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

2. Signal breakdown
* Memory corruption, weak/indirect corruption candidate: +1. The patch explicitly says unlocked driver_override access can cause UAF, but the visible primitive is stale string read/strcmp rather than controlled reclaim or overwrite.
* Real lifetime corruption: +1. The bug is a real lifetime race between driver_override replacement/free and match callback access.
* Reliable kernel crash / strong DoS: +1. A UAF in a driver match path can realistically produce KASAN splat, Oops, or kernel crash, although reliable exploitation is not demonstrated.
* Privileged kernel/device-management memory corruption path: +1. The corruption occurs in the driver binding/probing path for Hyper V vmbus devices.
* Hard or unreliable race / special timing required: -1. Triggering requires racing sysfs override changes with __driver_attach probing.
* Requires admin/root/CAP_* in typical deployments: -1 conservative refinement, not -2 for paranoid scoring. driver_override and device binding are usually privileged, but reduced capability root, service accounts, or delegated device management can make the practical boundary weaker than full host root.

3. Reachability analysis
The trigger is local through device driver_override manipulation and driver probing or rebinding. In typical deployments this is root or administrator controlled, so the conservative score treats it as privileged local. Namespaces and containers usually do not expose host vmbus device binding to untrusted users, but environments with delegated device management, reduced capability root, or service automation may lower the effective privilege barrier. The issue is not network reachable. It is relevant mainly on Hyper V guests or systems using vmbus devices.

4. Severity interpretation
This is not an ordinary cleanup bug because the commit explicitly identifies a UAF caused by unlocked access to driver_override. At the same time, the visible primitive is race dependent and appears limited to stale pointer read/use during matching, with no demonstrated attacker controlled reclaim, write primitive, callback hijack, or type confusion. Realistic impact is local DoS. Paranoid handling keeps it actionable because kernel lifetime bugs in driver binding paths are historically worth manual review.

5. One-sentence report phrase
A local race in Hyper V vmbus driver_override handling can let the driver match path read a freed override string during __driver_attach, causing a UAF and potential kernel crash, with paranoid impact treated as Actionable Moderate because reduced privilege device management scenarios may make PR lower than full host root.

6. Manual review recommendation
MANUAL CHECK REQUIRED. The patch explicitly fixes a UAF, and although practical LPE is not demonstrated, the lifetime race occurs in kernel driver binding logic and should not be auto-closed.

YES REQUIRES MANUAL CHECK

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

Patch: Drivers: hv: vmbus: use generic driver_override infrastructure [ Upstream
Commit: d1cb12ae81d2f7a58b0b1cfb51862afca98e6058
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d1cb12ae81d2f7a58b0b1cfb51862afca98e6058

Changed files:
  drivers/hv/vmbus_drv.c
  include/linux/hyperv.h

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=d1cb12ae81d2f7a58b0b1cfb51862afca98e6058

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

The original Linux kernel CVE announcement for CVE-2026-80676 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80676

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:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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: 4
  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).