[CVE-2026-80900][MODERATE 7.0] ASoC: SDCA: Make UMP message size check more robust [ Upstream

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

CVE: CVE-2026-80900
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ASoC: SDCA: Make UMP message size check more robust [ Upstream
Commit: fe5c53a952970ba15be8f512babd922e273579de
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fe5c53a952970ba15be8f512babd922e273579de
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80900
Analysis date: Fri, 04 Sep 2026 16:42:50 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-80900 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80900

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 7.0
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-2026-80900	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-80900 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-190;CWE-129;CWE-119;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L';BEST CVSS score: '5.8';DESCR 'An improper size check in the ASoC SDCA UMP helpers can allow a message offset larger than the UMP buffer length to pass validation because the old expression subtracts msg_offset from buf_len before comparing msg_len. If the values are unsigned or otherwise wrap, sdca_ump_read_message or sdca_ump_write_message may operate beyond the intended UMP buffer boundary. For the CVSS the PR:L is used because a local user or local service with access to the ALSA or SDCA UMP interface may be able to trigger the helper once an affected device exposes a bad message offset. The issue is not network reachable and appears tied to local audio hardware or firmware controlled SDCA descriptors. Impact is at least denial of service and in the grounded worst case may include limited confidentiality or integrity impact from out of bounds UMP buffer access.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	SIMPLEFIX HARDWARE  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	YES	NO	checked

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

ActionableScore=5
ActionableScoreLower=4

1. ActionableScore
* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**

2. Signal breakdown
* Local unprivileged trigger: +1. A local user or local service with access to the relevant ALSA or SDCA UMP path may be able to reach these helpers on affected hardware.
* Firmware-mediated external influence: +1. The dangerous condition depends on SDCA range values such as message offset and buffer length, which can be influenced by device or firmware provided descriptors.
* Memory corruption, weak or indirect corruption candidate: +1. The failed check protects read and write helpers from operating outside the intended UMP buffer, but the patch does not show an arbitrary target, attacker-controlled payload, reclaim primitive, or strong LPE primitive.
* Confidentiality impact plausible: +1. The read helper may read beyond the intended UMP buffer boundary in the invalid offset case.
* Integrity impact plausible: +1. The write helper may write beyond the intended UMP buffer boundary in the invalid offset case.
* Rare and difficult-to-reach subsystem/configuration: -1. The issue appears tied to SDCA/UMP-capable audio hardware and is not a broad default kernel path.
* Paranoid-only availability impact: +1. Out-of-bounds access in a kernel audio helper can plausibly cause a crash or device-level failure, even though the commit does not demonstrate a panic.

3. Reachability analysis
The bug is not network reachable. Realistic triggering requires an affected SDCA/UMP audio device plus a local path that causes sdca_ump_read_message() or sdca_ump_write_message() to process an invalid offset/length combination. Namespaces do not appear to materially lower or raise privileges here, because access is mediated by local device/audio interfaces rather than a network or namespace-native API. Call-site confidence: medium, because the changed read/write helpers are visible, but the full higher-level caller and user-control path are not included in the provided patch.

4. Severity interpretation
This is stronger than an ordinary Low because the broken validation guards both read and write operations and can allow out-of-bounds UMP buffer access. It does not look like an Important-class issue from the supplied patch alone, because there is no demonstrated controlled overwrite, UAF, type confusion, refcount abuse, callback control, or practical privilege escalation chain. The conservative interpretation is borderline/manual-review. The paranoid interpretation is Actionable Moderate because limited confidentiality or integrity impact is plausible from the bounds-check failure.

5. One-sentence report phrase
An improper size check in the ASoC SDCA UMP read and write helpers can allow an invalid message offset larger than the buffer length to bypass validation, potentially causing out-of-bounds UMP buffer access from a local audio or firmware-mediated path.

6. Manual review recommendation
MANUAL CHECK REQUIRED. The issue is a bounds-check bug protecting both read and write helpers, and the available patch context is insufficient to prove or rule out practical memory corruption impact.

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

Patch: ASoC: SDCA: Make UMP message size check more robust [ Upstream
Commit: fe5c53a952970ba15be8f512babd922e273579de
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fe5c53a952970ba15be8f512babd922e273579de

Changed files:
  sound/soc/sdca/sdca_ump.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=fe5c53a952970ba15be8f512babd922e273579de

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

The original Linux kernel CVE announcement for CVE-2026-80900 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80900

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:L/UI:N/S:U/C:L/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: 4
  Paranoid ActionableScore: 5

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 7.0

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).