[CVE-2026-72446][IMPORTANT] ALSA: usb-audio: qcom: reject stream disable with no active interface [ Upstream

[CVE-2026-72446][IMPORTANT] ALSA: usb-audio: qcom: reject stream disable with no active interface [ Upstream

[AL-KERNEL]

CVE: CVE-2026-72446
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: ALSA: usb-audio: qcom: reject stream disable with no active interface [ Upstream
Commit: 25a867aa5e67a84333fa6e5c21292c5bcff86b90
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=25a867aa5e67a84333fa6e5c21292c5bcff86b90
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72446
Analysis date: Sun, 16 Aug 2026 07:43:02 -0400
ActionableScore: 7
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A local unprivileged AF_QIPCRTR request can make the ALSA qcom USB audio offload disable path use a negative interface index, causing a NULL dereference or an out-of-bounds slab read and constrained 4 byte write with kernel crash and plausible privilege escalation risk.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-72446 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72446

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: IMPORTANT
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-2026-72446	IMPORTANT	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-129;*CWE-787;CWE-125;**CWE-476;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'ALSA qcom USB audio offload can access an invalid interface entry in handle_uaudio_stream_req() because the stream disable path uses a negative info_idx returned by info_idx_from_ifnum() without the guard used by the enable path. If the stream was never enabled, uadev info may be NULL and the computed info pointer can fault. If the card was enabled before, the same negative index can point before the allocated info array, allowing out of bounds slab reads and possible 4 byte zero writes to pipe fields. For the CVSS the PR:L is used because a local unprivileged userspace process can reach the request path through AF_QIPCRTR, while local code execution is still required. The issue is not directly network reachable. Impact is at least local denial of service via kernel crash and the out of bounds write makes memory corruption and privilege escalation plausible enough for manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)  SKIP CVE-2026-72446 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	WRITE OOB DANGER NULLPTR USB HARDWARE LINUS KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS KPANIC LOWERED_FROM_HIGH_BASED_ON_NULLPTR KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN6	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=7
ActionableScoreLower=5

## 1. ActionableScore

* Conservative score: 5
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

* Local unprivileged trigger: +1
  The commit states that the request is reachable from unprivileged local userspace over AF_QIPCRTR.

* Memory corruption, weak or constrained corruption primitive: +1 conservative
  Negative info_idx can index before uadev[pcm_card_num].info. The resulting access can cause OOB slab reads and a constrained 4 byte zero write to pipe fields.

* Memory corruption, strong primitive: +2 paranoid
  The paranoid interpretation treats the confirmed OOB write before a slab allocation as a real kernel memory corruption primitive requiring manual review, even though the payload is fixed and target control is limited.

* Weak LPE concern: +1 conservative
  The bug has an OOB write into adjacent slab memory, but no demonstrated reclaim, object replacement, arbitrary write, callback control, or type confusion.

* Privilege escalation plausible: +2 paranoid
  Local unprivileged reachability plus kernel slab OOB write makes LPE plausible enough for Important-candidate triage, although not proven.

* Reliable kernel crash / strong DoS: +1
  If .info is NULL, the computed pointer can fault on info->data_ep_pipe and cause a kernel oops.

* Integrity impact plausible: +1
  The disable path may clear fields through an out-of-bounds pointer, creating a limited write primitive.

* Confidentiality impact plausible: +1 paranoid only
  OOB slab reads of data_ep_pipe and sync_ep_pipe exist, but no user-visible disclosure path is shown. Counted only in the paranoid score.

* Rare AND difficult-to-reach subsystem/configuration: -1
  This is Qualcomm USB audio offload specific and depends on the qcom usb-audio offload path and AF_QIPCRTR environment, not a broad default kernel path.

* Call-site confidence: high
  The vulnerable dereference and the new negative-index guard are directly visible in handle_uaudio_stream_req().

## 3. Reachability analysis

The trigger is local, not network reachable. The relevant request path is described as reachable from unprivileged local userspace through AF_QIPCRTR, so PR:L is the correct practical assumption rather than PR:H. Namespaces or containers may matter if AF_QIPCRTR is exposed inside the container, but the bug still requires local code execution. The affected code is device and platform specific, so exposure is narrower than a generic ALSA or USB core bug.

## 4. Severity interpretation

This is not an ordinary NULL dereference only. The first case is a reliable local DoS when .info is NULL, but the second case is more serious because an already allocated .info array allows a negative index to produce OOB slab reads and a constrained 4 byte zero write. Realistic exploitation evidence for LPE is not demonstrated, but the local unprivileged OOB write is enough to avoid auto-closing and to require manual analysis.

## 5. One-sentence report phrase

A local unprivileged AF_QIPCRTR request can make the ALSA qcom USB audio offload disable path use a negative interface index, causing a NULL dereference or an out-of-bounds slab read and constrained 4 byte write with kernel crash and plausible privilege escalation risk.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: confirmed local unprivileged reachability plus OOB slab read/write memory corruption. The write is constrained, but it is still beyond a simple DoS and should be reviewed for slab adjacency, object layout, and practical LPE feasibility.

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

Patch: ALSA: usb-audio: qcom: reject stream disable with no active interface [ Upstream
Commit: 25a867aa5e67a84333fa6e5c21292c5bcff86b90
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=25a867aa5e67a84333fa6e5c21292c5bcff86b90

Changed files:
  sound/usb/qcom/qc_audio_offload.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=25a867aa5e67a84333fa6e5c21292c5bcff86b90

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

The original Linux kernel CVE announcement for CVE-2026-72446 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72446

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:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 5
  Paranoid ActionableScore: 7

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).