[CVE-2026-93788][LOW] wifi: iwlwifi: acpi: validate WGDS table revision index [ Upstream

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-93788
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: wifi: iwlwifi: acpi: validate WGDS table revision index [ Upstream
Commit: 2fc98ab6fe8acabd13eb09dc17426a33cf9f27f7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2fc98ab6fe8acabd13eb09dc17426a33cf9f27f7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93788
Analysis date: Thu, 24 Sep 2026 13:15:33 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-93788 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93788

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: LOW
Manual review required: NO

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

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

CVE-2026-93788	LOW	https://www.kernelcve.org/list/?q=CVE-2026-93788 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';CWE-1284;CWE-758;*CWE-20;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:N';BEST CVSS score: '1.9';DESCR 'An invalid revision index from an ACPI WGDS package can reach BIT(tbl_rev) in the iwlwifi ACPI parser without a bounds check. A revision value outside the width of the revisions bitmap can cause an undefined shift and may result in incorrect table processing or an UBSAN warning on diagnostic kernel configurations. For the CVSS the PR:H is used because reliable triggering normally requires control of platform ACPI data or firmware. The issue is not network reachable through normal WiFi traffic. No out of bounds access use after free or memory write primitive is shown by the patch. Impact is normally none. A limited availability impact is possible only in configurations that treat undefined behavior diagnostics as fatal.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	YES	REMOTE SIMPLEFIX NETWORK  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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

ActionableScore=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +0 No concrete corruption primitive. The patch adds bounds validation before `BIT(tbl_rev)` and prevents an invalid shift count.
* +0 No UAF, stale reference, refcount mutation, OOB memory access, write primitive, disclosure path, authorization bypass, or ownership violation is established.
* +0 No reliable kernel crash is established. An undefined shift may produce an UBSAN diagnostic in suitable diagnostic builds, but the supplied evidence does not establish panic or host-wide denial of service.
* +0 Remote reachability is not established. The revision value originates from a platform ACPI WGDS package, not normal WiFi traffic.
* +0 Local unprivileged reachability is not established. The evidence does not show that an ordinary user can modify the relevant ACPI package or induce the invalid revision value.
* +0 No privilege penalty is applied. Control of platform ACPI data or firmware is mentioned as a likely prerequisite, but the supplied evidence does not positively establish the complete privilege boundary.
* Not awarded: controlled reclaim, arbitrary write, confidentiality impact, integrity impact, privilege escalation, and structured stale-object leverage are not demonstrated.
* Not awarded: availability impact. Fatal UBSAN behavior is configuration dependent and not established as a practical kernel crash path.
* No floors or caps were applied.

3. Reachability analysis

The affected value is parsed from the ACPI WGDS package used by the Intel iwlwifi ACPI support path. The vulnerable operation is an invalid bit shift in `BIT(tbl_rev)` when firmware or platform-provided ACPI data reports a negative or out-of-range revision index.

Normal remote WiFi traffic does not directly control this ACPI table, so this is not network reachable through ordinary wireless packet processing. The supplied patch does not establish that an ordinary local user can alter ACPI firmware data, inject the relevant ACPI package, or otherwise reach the invalid-table condition.

Platform firmware modification, ACPI override mechanisms, or equivalent system configuration control may be required, but the complete privilege model is not visible. Therefore HostAdminRequired is UNKNOWN rather than YES. No namespace-scoped path is shown, so NamespaceScopedPrivilege is UNKNOWN. No race, special hardware trigger, or prior host-side runtime setup is established beyond the existence of affected Intel wireless hardware and platform ACPI data.

4. Primitive and severity interpretation

The exact defect is missing validation of an ACPI-supplied revision index before it is used as the shift operand in `BIT(tbl_rev)`. An out-of-range shift count is undefined behavior in C and can result in architecture-dependent behavior, compiler-dependent behavior, or an UBSAN warning.

This is not a UAF, lifetime violation, OOB access, refcount defect, active-object corruption, semantic ownership violation, or security-boundary bypass. The patch only rejects invalid revision values before testing the corresponding bit in the supported-revision bitmap.

The demonstrated practical consequence is limited to incorrect ACPI table handling or a diagnostic undefined-behavior report. A fatal diagnostic configuration could theoretically turn the condition into limited availability impact, but that outcome is not sufficiently established for ActionableScore points.

PrimitiveClass is NONE. ImportantCandidate is NO because no meaningful corruption or authorization primitive remains unresolved. AutoDowngradeAllowed is YES because the patch represents input validation for firmware-originated metadata and there is no demonstrated exploitation leverage beyond invalid-shift behavior.

5. One-sentence report phrase

An invalid ACPI WGDS revision index could reach BIT(tbl_rev) without bounds validation and cause undefined shift behavior, but no memory corruption, direct network trigger, or practical privilege-escalation primitive is established.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch is a validation-only fix for an invalid firmware-provided bitmap index, with no demonstrated kernel memory corruption, crash, disclosure, integrity impact, or authorization bypass.

7. Call-site confidence

Call-site confidence: medium

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

Patch: wifi: iwlwifi: acpi: validate WGDS table revision index [ Upstream
Commit: 2fc98ab6fe8acabd13eb09dc17426a33cf9f27f7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2fc98ab6fe8acabd13eb09dc17426a33cf9f27f7

Changed files:
  drivers/net/wireless/intel/iwlwifi/fw/acpi.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=2fc98ab6fe8acabd13eb09dc17426a33cf9f27f7

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

The original Linux kernel CVE announcement for CVE-2026-93788 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93788

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:N
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 1.9

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: unknown
  Paranoid ActionableScore: 0

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).