[CVE-2026-64243][MODERATE REGULAR] ASoC: codecs: simple-mux: Fix enum control bounds check [ Upstream

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

CVE: CVE-2026-64243
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ASoC: codecs: simple-mux: Fix enum control bounds check [ Upstream
Commit: 6fb653b62f169f6050fac45b56bf21ad097e19f6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6fb653b62f169f6050fac45b56bf21ad097e19f6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64243
Analysis date: Fri, 24 Jul 2026 12:29:41 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline Moderate. Manual review recommended
Manual review required: YES

Summary:
An off-by-one bounds check in the ASoC simple-mux enum control can allow a local ALSA control user to store an invalid mux value that may be used as a DAPM enum text index, causing incorrect mux or GPIO state and possibly a local kernel DoS on affected hardware.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-64243 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64243

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
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CVE-2026-64243	MODERATE	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:N/I:L/A:H';CWE-129;CWE-125;*CWE-20;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '6.1';DESCR 'An off by one bounds check in the ASoC simple-mux enum control can accept an invalid zero based mux value equal to the number of enum items. That invalid value can be stored as the mux state, passed to the GPIO setter, and later used by the DAPM mux update path as an index into the enum text array. This creates a local out of bounds read risk and can also cause incorrect audio routing or invalid GPIO state on affected hardware. For the CVSS the PR:L is used because triggering requires a local user or process with access to the ALSA sound control interface rather than full administrative privileges. The issue is not network reachable. Impact is mainly limited integrity impact and possible denial of service if the invalid enum text access causes a kernel fault.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Moderate. Manual review recommended (with actual score 2)  SKIP CVE-2026-64243 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	OOB SIMPLEFIX HARDWARE  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Borderline Moderate. Manual review recommended**

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local user or process with access to the ALSA control interface may set the enum control value.
* Limited read-only OOB / invalid enum index: +0. The patch shows an off-by-one enum validation bug and use as an index into the enum text array, but no write primitive, reclaim primitive, callback control, or type confusion is shown.
* Rare / hardware-specific subsystem: -1. The affected code is an ASoC simple-mux codec path and depends on affected hardware or board configuration.
* Integrity impact plausible: +1. An invalid mux value can be stored and passed to the GPIO setter, potentially causing incorrect audio routing or invalid GPIO state.

Paranoid additional signals:

* Weak/indirect corruption candidate: +1. The unchecked enum value can propagate into a kernel array index in the DAPM mux update path.
* Availability impact plausible: +1. If the invalid enum text access resolves to an invalid pointer or otherwise faults, a local kernel crash is possible, although not demonstrated as reliable.

No signals awarded:

* No remote reachable signal. This is not network-triggerable.
* No strong memory corruption signal. The patch shows an OOB read/indexing candidate, not OOB write, UAF, double free, arbitrary write, or refcount takeover.
* No LPE signal. There is no demonstrated reclaim, overwrite, callback dispatch, type confusion, or privilege escalation primitive.
* No high-control API bonus. ALSA control configuration alone is not enough under the device-object API rule.

## 3. Reachability analysis

The bug is reachable through a local ALSA control operation on systems that expose the simple-mux codec control. In typical desktop or embedded deployments, access may be available to local users through audio device ACLs, a sound group, or a session manager, so PR:L is a reasonable paranoid CVSS interpretation. It does not require CAP_SYS_ADMIN in the common audio-control model, but it does require that the affected ASoC codec and board configuration are present. Containers usually do not expose host ALSA controls unless devices are explicitly passed through. The path is not default-reachable on arbitrary servers and is not remotely reachable.

Call-site confidence: medium. The commit message describes the downstream DAPM mux update path and enum text indexing, but the full surrounding call graph is not included in the supplied diff.

## 4. Severity interpretation

This behaves like a low-to-borderline Moderate kernel issue rather than an Important-class vulnerability. The theoretical concern is a local OOB read or invalid pointer use in kernel audio control handling, with possible kernel crash on affected hardware. Realistic exploitation evidence is weak because the patch does not show attacker-controlled overwrite, UAF reuse, type confusion, or a practical privilege escalation path. The issue should not be treated as a strong LPE candidate, but manual review is reasonable because kernel OOB indexing is present and hardware-specific behavior may affect crashability.

## 5. One-sentence report phrase

An off-by-one bounds check in the ASoC simple-mux enum control can allow a local ALSA control user to store an invalid mux value that may be used as a DAPM enum text index, causing incorrect mux or GPIO state and possibly a local kernel DoS on affected hardware.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Manual review is recommended because the bug includes a kernel OOB index candidate, but it is not a strong Important candidate without evidence of write corruption, UAF reuse, type confusion, or practical privilege escalation.

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UPSTREAM PATCH SUMMARY
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Patch: ASoC: codecs: simple-mux: Fix enum control bounds check [ Upstream
Commit: 6fb653b62f169f6050fac45b56bf21ad097e19f6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6fb653b62f169f6050fac45b56bf21ad097e19f6

Changed files:
  sound/soc/codecs/simple-mux.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=6fb653b62f169f6050fac45b56bf21ad097e19f6

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

The original Linux kernel CVE announcement for CVE-2026-64243 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64243

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:L/UI:N/S:U/C:N/I:L/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
  The Best / paranoid CVSS score: 6.1

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: 1
  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).