* [CVE-2026-93178][MODERATE REGULAR] drm/amdgpu/pm/powerplay: bounds-check voltage index in SMU7 lookup [ Upstream
@ 2026-09-18 13:00 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-18 13:00 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-93178
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/amdgpu/pm/powerplay: bounds-check voltage index in SMU7 lookup [ Upstream
Commit: d9ef085114d1e3c2c1f869c0bdb275a7b358ce8b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d9ef085114d1e3c2c1f869c0bdb275a7b358ce8b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93178
Analysis date: Fri, 18 Sep 2026 09:00:46 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
AMDGPU SMU7 powerplay code used VBIOS-derived voltage indexes without bounds checks, allowing malformed firmware tables to trigger an internal OOB read and potentially cause GPU power-management failure or device-local DoS.
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ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93178 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93178
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-93178 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-93178 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:H/PR:H/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '5.8';DESCR 'A bounds check was missing when SMU7 powerplay code used VBIOS parsed vddInd and vddcInd values as indexes into AMDGPU voltage lookup tables. A malformed or malicious VBIOS table could make the driver read past the end of a voltage table and use the resulting value for GPU power management state. For the CVSS the PR:L in the paranoid score covers environments where a local user can trigger driver reprobe or GPU management paths while malformed firmware data is already present. In typical deployments practical triggering is more restricted and may require administrator or physical control over the GPU firmware. The issue is not network reachable. Impact is mainly local denial of service or device instability, with limited confidentiality and integrity impact considered only for the paranoid score because the primitive is an out-of-bounds read rather than a write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) MAYBE WRITE OOB SIMPLEFIX HARDWARE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 - - checked
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ACTIONABLESCORE ANALYSIS
======================================================================
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. VBIOS-parsed `vddInd` and `vddcInd` values are used as unchecked indexes into voltage lookup tables, establishing an OOB read candidate.
* +1 Firmware-mediated external influence. The problematic indexes come from VBIOS / firmware-derived tables, so attacker influence is materially mediated by firmware or device state rather than direct local or remote input.
Paranoid additional signal:
* +1 Limited availability / device-state concern. The OOB-read value is used as a voltage value in GPU power-management tables, so malformed data could plausibly cause driver initialization failure, device instability, or local GPU DoS.
Non-awarded signals:
* RealUAF not awarded. No stale pointer or post-lifetime object use is established.
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Kernel write primitive not demonstrated.
* Confidentiality not awarded. The OOB read is internal and no user-visible disclosure path is shown.
* Integrity not awarded beyond the weak device-state concern. The patch does not establish unauthorized modification of protected kernel state or another principal's data.
* Reliable kernel crash not awarded. The patch supports invalid indexing and possible bad power-management state, but not a demonstrated host-wide panic.
* Remote reachability not established.
* Local unprivileged trigger not awarded. Supplying malformed VBIOS data is not shown to be reachable by an ordinary local user.
* No host-admin penalty applied because host-admin-equivalent privilege is plausible for flashing or overriding VBIOS, but not positively established as the only possible attacker model.
## 3. Reachability analysis
The vulnerable input is firmware-derived VBIOS table data parsed by the AMDGPU SMU7 powerplay code. A practical attacker would need malformed or malicious VBIOS contents, a compromised device or firmware path, or a system state where such firmware data is already present.
Ordinary local-user reachability is not established from the supplied patch. A local user may be able to trigger driver probing or GPU management paths in some environments, but the complete chain for supplying or controlling the malformed VBIOS table below host-admin privilege is not shown.
Host administrator or physical/device-firmware control is plausible for intentionally installing malformed VBIOS, but the evidence does not prove that host-admin-equivalent privilege is strictly required in all models. Therefore `HostAdminRequired=UNKNOWN`.
The issue is not namespace-scoped. Network namespaces, user namespaces, or container-local capabilities do not appear relevant.
No direct network trigger is established. No race condition is involved. The hardware dependency is GPU-specific, but common GPU driver code should not be treated as rare hardware by itself.
## 4. Primitive and severity interpretation
The exact primitive is an unchecked firmware-derived index causing a read past the end of AMDGPU voltage lookup tables. The read result is then interpreted as a voltage value and written into GPU power-management dependency tables.
This is a read-only OOB / invalid structured-data interpretation issue, not a UAF, not a double release, and not an OOB write. The main demonstrated consequence is invalid driver/device state. A local device DoS or GPU instability is plausible, but a host-wide kernel crash, privilege escalation, or information disclosure is not established.
Primitive class is `CLASS_C` because the established behavior is invalid-state / weak OOB-read behavior without an independently useful exploitation primitive.
`ImportantCandidate=NO` because there is no demonstrated controlled corruption, UAF, ownership violation, authorization bypass, information leak, or practical LPE chain.
`AutoDowngradeAllowed=YES` because this appears suitable for ordinary low / moderate handling unless additional evidence shows a user-controlled firmware path, host-wide crash, disclosure, or stronger corruption primitive.
Likely operational severity: Low to borderline Moderate. Manual review is still recommended because firmware-derived OOB reads in kernel driver initialization can sometimes hide stronger device-state consequences.
## 5. One-sentence report phrase
AMDGPU SMU7 powerplay code used VBIOS-derived voltage indexes without bounds checks, allowing malformed firmware tables to trigger an internal OOB read and potentially cause GPU power-management failure or device-local DoS.
## 6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Reason: the issue is not an Important candidate from the supplied evidence, but the OOB read is firmware-derived and affects GPU power-management state, so a short manual check is useful to confirm whether any product-specific path allows below-admin control of VBIOS data or causes host-wide failure.
## 7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: drm/amdgpu/pm/powerplay: bounds-check voltage index in SMU7 lookup [ Upstream
Commit: d9ef085114d1e3c2c1f869c0bdb275a7b358ce8b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d9ef085114d1e3c2c1f869c0bdb275a7b358ce8b
Changed files:
drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_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=d9ef085114d1e3c2c1f869c0bdb275a7b358ce8b
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93178 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93178
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:L/A:L
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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