[CVE-2026-93177][MODERATE REGULAR] drm/amdgpu/pm/powerplay: bounds-check voltage index in Vega10 lookup [ Upstream

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

CVE: CVE-2026-93177
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/amdgpu/pm/powerplay: bounds-check voltage index in Vega10 lookup [ Upstream
Commit: 206e478810d6af50b25d8da72e3af8d55a014365
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=206e478810d6af50b25d8da72e3af8d55a014365
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93177
Analysis date: Thu, 17 Sep 2026 23:06:05 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
Vega10 PowerPlay can read outside voltage lookup tables because VBIOS-derived voltage indexes are used without bounds checks, which may cause GPU driver failure or DoS but does not establish UAF, write corruption, network reachability, or privilege escalation.

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

The original Linux kernel CVE announcement for CVE-2026-93177 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93177

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 REGULAR
Manual review required: YES

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
======================================================================

CVE-2026-93177	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-93177 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-129;CWE-125;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'Vega10 powerplay code uses voltage indexes parsed from VBIOS tables to access vddc, vddci, and vddmem lookup tables without checking the table counts. A malformed or compromised VBIOS can therefore drive an out-of-bounds read in the amdgpu kernel driver during power management table processing, which may cause a kernel crash or incorrect voltage data to be used. For the CVSS the PR:L is used for the paranoid score because a local low privilege user may be able to reach GPU driver paths on a system where malformed firmware or a compromised device is already present, although creating or installing the bad VBIOS normally requires admin or physical control. The issue is not network reachable. Impact is primarily denial of service, with limited confidentiality or integrity impact possible from an out-of-bounds kernel read and corrupted power table values. Vega10 systems are affected only when the relevant AMDGPU powerplay path and malformed VBIOS-derived tables are present.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3)  SKIP CVE-2026-93177 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	WRITE OOB HARDWARE  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

## 1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2. No floor or cap applied.
* Raw paranoid score: 3
* Paranoid score: 3. No floor or cap applied.
* Final recommended bucket: **Borderline / manual review recommended**::

## 2. Signal breakdown

Conservative signals:

* +1 Weak / indirect corruption candidate: Vega10 PowerPlay uses VBIOS-derived voltage indexes to index vddc, vddci, and vddmem lookup tables without bounds checks.
* +1 Firmware-mediated external influence: the problematic indexes come from VBIOS-parsed tables, so external or device-firmware-controlled data is involved, but this is not direct network or ordinary userspace input.

Paranoid additional signal:

* +1 Realistic DoS / device instability concern: an out-of-bounds kernel read or wrong voltage value propagation may cause driver failure, GPU instability, or potentially a kernel fault, although a reliable host-wide crash is not demonstrated in the supplied patch.

Non-awarded signals:

* +0 RealUAF: no use-after-free, stale reference, RCU lifetime bug, or repeated release/refcount mutation is established.
* +0 Strong corruption: no OOB write, arbitrary write, controlled reclaim, type confusion, callback control, or refcount takeover is shown.
* +0 Confidentiality: no disclosure path is shown for the out-of-bounds read.
* +0 Integrity: incorrect voltage table values may affect device behavior, but no unauthorized modification of protected kernel state or another principal's data is established.
* +0 Remote reachability: the input is firmware/VBIOS mediated, not packet or network reachable.
* +0 Local unprivileged trigger: below-host-admin reachability for installing or controlling malformed VBIOS data is not established.
* No privilege penalty applied: host-admin-equivalent requirement is plausible but not positively established by the supplied evidence.
* No hardware rarity penalty applied: Vega10/AMDGPU is hardware-specific, but the prompt requires concrete evidence of rare or physical-only access before subtracting.

## 3. Reachability analysis

The vulnerable path is in the AMDGPU Vega10 PowerPlay table processing code. The attacker-controlled part, if any, is the VBIOS-derived voltage index data. A malformed or compromised VBIOS can cause indexes such as vddInd, vddciInd, or mvddInd to exceed the corresponding lookup table count.

The complete attacker model is unresolved. Creating or installing a malicious VBIOS commonly implies administrative, physical, firmware, or device-supply-chain control, but the supplied patch does not positively prove host-admin-equivalent privilege is always required. Therefore HostAdminRequired is UNKNOWN rather than YES.

This is not namespace-scoped. Network namespaces, user namespaces, and delegated capabilities are not relevant to the complete trigger chain. NamespaceScopedPrivilege is NO.

No direct network path is established. No ordinary local user path is established. The issue is best treated as firmware-mediated and hardware-path dependent.

Race repeatability is not relevant. This is not a timing race.

## 4. Primitive and severity interpretation

The exact primitive is an unchecked index into kernel lookup tables, producing a read outside the intended voltage lookup table bounds. This is a read-only OOB / invalid indexed access candidate, not a lifetime bug.

The stale-object and repeated-release rules do not apply:

* first release can end lifetime: not applicable
* exact same reference survives: not applicable
* second lifetime/refcount mutation: not applicable
* concrete repeated release/refcount +1: not awarded
* FLOOR 5: not applied

PrimitiveClass is CLASS_C because the demonstrated behavior is primarily invalid indexed access with possible crash or invalid device state, without an independently useful corruption primitive.

The demonstrated consequence is prevention of out-of-bounds reads from malformed VBIOS-derived tables. The plausible operational consequence is GPU driver failure, device instability, or DoS. A stronger consequence such as privilege escalation is speculative and not supported by the patch.

ImportantCandidate is NO because no Class A primitive and no strong Class B lifetime/corruption primitive is established. ManualReview is RECOMMENDED because this is still kernel OOB access from firmware-derived data and may deserve human confirmation for affected deployment models. AutoDowngradeAllowed is YES because there is no UAF, no write primitive, no authorization bypass, no controlled corruption, and no unresolved repeated lifetime/refcount mutation.

Likely operational severity: ordinary to borderline Moderate, depending on whether malformed VBIOS input is realistically attacker-controlled in the evaluated product.

## 5. One-sentence report phrase

Vega10 PowerPlay can read outside voltage lookup tables because VBIOS-derived voltage indexes are used without bounds checks, which may cause GPU driver failure or DoS but does not establish UAF, write corruption, network reachability, or privilege escalation.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: the patch fixes kernel out-of-bounds reads from firmware-derived data, but current evidence supports only firmware-mediated DoS or device instability rather than a strong exploitation primitive.

## 7. Call-site confidence

Call-site confidence: medium

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

Patch: drm/amdgpu/pm/powerplay: bounds-check voltage index in Vega10 lookup [ Upstream
Commit: 206e478810d6af50b25d8da72e3af8d55a014365
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=206e478810d6af50b25d8da72e3af8d55a014365

Changed files:
  drivers/gpu/drm/amd/pm/powerplay/hwmgr/vega10_hwmgr.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=206e478810d6af50b25d8da72e3af8d55a014365

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

The original Linux kernel CVE announcement for CVE-2026-93177 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93177

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: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: 2
  Paranoid ActionableScore: 3

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 REGULAR

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).