* [CVE-2026-80964][MODERATE REGULAR] ALSA: virmidi: Check card index validity at probe
@ 2026-09-11 20:37 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-11 20:37 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-80964
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ALSA: virmidi: Check card index validity at probe
Commit: 43f161c53279adac0517cf1c443e531e738b54ce
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=43f161c53279adac0517cf1c443e531e738b54ce
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80964
Analysis date: Fri, 11 Sep 2026 16:37:51 -0400
ActionableScore: 2
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-2026-80964 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80964
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-2026-80964 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-80964 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 virmidi probe can perform out-of-bounds array access because devptr id is trusted and used as an index into card parameter arrays such as index and id. The normal devices created by the driver use valid ids, but manual sysfs binding can provide an invalid value such as -1 and reach the OOB access during probe. For the CVSS the PR:L is used in the paranoid score because some deployments may delegate sysfs device binding or similar device management to a reduced capability local account instead of full host root. The issue is not network reachable and requires local device control rather than packet input. Impact is at least local denial of service through kernel fault or broken device initialization. Because this is kernel OOB access, limited confidentiality or integrity impact should be reviewed manually even though no direct write primitive is shown.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) YES OOB SIMPLEFIX HARDWARE LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::
No floor or cap changed the score.
2. Signal breakdown
Positive signals:
* +1 Weak / indirect corruption candidate. `devptr->id` is used as an unchecked array index into `index[]`, `id[]`, and related card parameters.
* +1 Kernel invalid access / local DoS concern. The patch establishes OOB access in kernel probe code, and bad values may cause broken initialization or kernel fault behavior.
Negative signals:
* No explicit numeric subtraction was applied beyond keeping the score in the ordinary range, because the host-admin requirement is already reflected in severity interpretation rather than used to drive the score below the concrete OOB-access baseline.
Important non-awarded signals:
* RealUAF not awarded. No lifetime or stale-object use is shown.
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* OOB write not demonstrated.
* Confidentiality not awarded. The OOB read is internal and no user-visible disclosure path is established.
* Integrity not awarded. No unauthorized write or protected-state modification primitive is established.
* Remote reachability not established.
* Local unprivileged trigger not established.
* NamespaceScopedPrivilege not established. Sysfs manual driver binding is not shown to be fully namespace-scoped.
* Strong LPE or weak LPE concern not awarded. The bug class is OOB access, but no meaningful exploitation leverage beyond invalid indexing is established.
3. Reachability analysis
The vulnerable path is reached during `snd_virmidi_probe()` when a manually bound platform device supplies an invalid `devptr->id`, such as `-1`.
The normal virmidi devices created by the driver use valid IDs, so the interesting trigger is manual sysfs binding. Writing to sysfs driver bind interfaces is normally host-root or host-admin-equivalent device-management functionality. The supplied context does not establish that an ordinary local user can perform the complete bind operation.
Namespace-scoped privilege is not established. The input does not show that the relevant sysfs platform-device bind operation can be completed inside an attacker-created user namespace or with only namespace-local capabilities.
No network trigger is present. No special rare hardware requirement is established beyond use of the ALSA virmidi driver.
This is not a race.
4. Primitive and severity interpretation
The exact primitive is unchecked index use in kernel probe code. `devptr->id` can be outside `0..SNDRV_CARDS-1`, and then `index[dev]`, `id[dev]`, and related arrays may be accessed out of bounds.
This is best classified as CLASS_C: invalid kernel access / OOB indexing with primarily crash or invalid-state consequences. It is not a real UAF, not a repeated release/refcount mutation, and not an active structured stale-object bug.
Demonstrated consequence is OOB access during device probe. Practical consequence is likely local DoS or broken device initialization if the invalid access leads to a fault or invalid parameters.
Speculative consequence would be limited information or integrity impact from reading adjacent kernel data as module parameters, but the patch does not establish a disclosure path, write primitive, or attacker-controlled target. Therefore this does not become CLASS_A or CLASS_B.
ImportantCandidate=NO because no strong corruption, lifetime, authorization, COW, boundary-bypass, LPE, or repeated lifetime/refcount primitive is established.
AutoDowngradeAllowed=YES because this is a host-admin-reachable OOB indexing issue with no demonstrated useful corruption primitive beyond local invalid access.
Likely operational severity: ordinary Moderate / Low-like for security triage, though manual review is reasonable because it is still kernel OOB access.
5. One-sentence report phrase
ALSA virmidi probe trusts devptr id as a card index, so manual sysfs binding with an invalid id such as -1 can trigger kernel OOB access in card parameter arrays, requiring host device-management privileges and primarily causing local DoS or broken initialization.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Reason: kernel OOB access is present, but the trigger appears host-admin-gated through manual sysfs device binding and no disclosure, write, UAF, or privilege-escalation primitive is established.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: ALSA: virmidi: Check card index validity at probe
Commit: 43f161c53279adac0517cf1c443e531e738b54ce
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=43f161c53279adac0517cf1c443e531e738b54ce
Commit description:
virmidi 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: [email protected]
Signed-off-by: Takashi Iwai <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
sound/drivers/virmidi.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=43f161c53279adac0517cf1c443e531e738b54ce
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80964 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80964
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: 2
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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