[CVE-2026-80969][MODERATE REGULAR] ALSA: mpu401: Check card index validity at probe

[CVE-2026-80969][MODERATE REGULAR] ALSA: mpu401: Check card index validity at probe

[AL-KERNEL]

CVE: CVE-2026-80969
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ALSA: mpu401: Check card index validity at probe
Commit: 76b6bc38d0f310c0ae1b2a2ebabe2947d92c601a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=76b6bc38d0f310c0ae1b2a2ebabe2947d92c601a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80969
Analysis date: Fri, 11 Sep 2026 18:11:05 -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-2026-80969 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80969

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: NO

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

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

CVE-2026-80969	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-80969 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: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: '6.6';DESCR 'ALSA mpu401 probe trusted the platform device id as an array index for card parameters such as index, port, irq, and id. If a device is manually bound through sysfs with an invalid id such as -1, the driver can access those arrays out of bounds during probe, which may lead to a kernel crash and possibly unintended use of adjacent kernel data. For the CVSS the PR:L is used for the paranoid score because reliable triggering needs local ability to bind a device to the driver, and in some deployments this may be delegated to a reduced capability root, service account, or container management context rather than full host administration. The issue is not network reachable. Impact is primarily local denial of service. Because the bug is an out of bounds kernel access, limited confidentiality or integrity impact is kept in the paranoid score and the case should be manually reviewed.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	YES	OOB SIMPLEFIX HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	NO	NO	checked

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

ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
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**::

No floor or cap changed the score. Arithmetic is clamped at 0 after applying the host-admin privilege penalty.

2. Signal breakdown

Positive signals:

* +1 Weak or indirect corruption candidate. `snd_mpu401_probe()` trusted `devptr->id` as an array index and could read outside ALSA card parameter arrays such as `index[]`, `port[]`, `irq[]`, and `id[]`.
* +1 Plausible local DoS in paranoid view. OOB values may be consumed as probe parameters and could plausibly cause invalid state or a kernel fault.

Negative signals:

* -2 Host-admin-equivalent privilege required. The described trigger is manual driver binding through sysfs, which is normally writable only by host root or an equivalent host administrator.

Non-awarded signals:

* Real UAF not awarded. No object lifetime violation is shown.
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* OOB write not demonstrated.
* Confidentiality not awarded because no user-visible disclosure path is shown.
* Integrity not awarded because the patch shows OOB reads of parameters, not unauthorized modification of protected state.
* Network reachability not established.
* Namespace-scoped privilege not established.
* Extra availability not awarded because any crash would be the same local failure already considered.
* ImportantCandidate not awarded because the primitive is host-admin-gated and lacks a useful exploitation primitive beyond invalid OOB parameter access.

3. Reachability analysis

The reachable path is `snd_mpu401_probe()` when an mpu401 platform device is manually bound through the sysfs driver interface with an invalid device id such as `-1`. That operation is a local control-plane action and normally requires host root or equivalent host administrative access.

There is no evidence that an ordinary local user can create or bind the relevant platform device. There is no evidence that the complete operation is namespace-scoped. The vulnerable path is not network reachable. No special race is involved. The affected driver is hardware or legacy-device specific, but no separate rare-hardware penalty is needed because host-admin gating already dominates practical risk.

4. Primitive and severity interpretation

The exact primitive is unchecked array indexing using a platform device id. The likely access is read-only OOB access to static module parameter arrays, followed by use of those values as driver probe configuration.

This is not an active structured UAF and not fixed stale storage. There is no concrete repeated release or refcount operation. The demonstrated issue is invalid OOB access and possible crash or bad initialization during a host-admin-controlled probe path.

PrimitiveClass is CLASS_C because the supplied evidence supports invalid-state or crash-style behavior, not an independently useful corruption primitive. ImportantCandidate is NO because no below-host-admin attacker, authorization bypass, UAF, controlled write, disclosure, or LPE path is established. AutoDowngradeAllowed is YES because the issue is host-admin-gated and does not preserve meaningful unresolved Important-grade exploitation leverage.

5. One-sentence report phrase

ALSA mpu401 probe could use an invalid platform device id as an array index during sysfs manual binding, causing local OOB parameter access and possible DoS, but practical triggering appears to require host-admin-equivalent control.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch shows a host-admin-gated sysfs bind scenario with OOB parameter access but no UAF, no write primitive, no disclosure path, no network reachability, and no demonstrated privilege boundary bypass.

7. Call-site confidence

Call-site confidence: medium

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

Patch: ALSA: mpu401: Check card index validity at probe
Commit: 76b6bc38d0f310c0ae1b2a2ebabe2947d92c601a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=76b6bc38d0f310c0ae1b2a2ebabe2947d92c601a

Commit description:

mpu401 driver blindly trusts that the given devptr->id value is within
the proper card index range at probe.  It's OK for the devices the
driver itself creates at the module probe time, but if the device is
bound manually via sysfs interface, this could be -1 as "none", and
this leads to OOB access for index[] and other parameters.

Add a sanity check for the card index and warn/correct it if it's a
value out of the range.

Cc: stable@vger.kernel.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260806153227.1460166-3-tiwai@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  sound/drivers/mpu401/mpu401.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=76b6bc38d0f310c0ae1b2a2ebabe2947d92c601a

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

The original Linux kernel CVE announcement for CVE-2026-80969 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80969

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:L/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 6.6

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: 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).