* [CVE-2026-80812][MODERATE REGULAR] ALSA: dummy: Check card index validity at probe
@ 2026-09-04 16:42 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-04 16:42 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-80812
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ALSA: dummy: Check card index validity at probe
Commit: b7579e86afcec932e169d10e2d603abed8dd2fdf
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b7579e86afcec932e169d10e2d603abed8dd2fdf
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80812
Analysis date: Fri, 04 Sep 2026 12:42:47 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline manual review recommended
Manual review required: YES
Summary:
ALSA dummy driver probe used an unvalidated platform device id as an array index, allowing a local actor with device binding control to trigger OOB reads and possible kernel crash, with limited confidentiality concern but no demonstrated privilege escalation primitive.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80812 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80812
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-80812 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-80812 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:N/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: '6.1';DESCR 'snd_dummy_probe used the platform device id as an array index without validating that it is within the ALSA card range. A manually bound platform device can use id -1, causing OOB reads from module parameter arrays such as index and id before snd_devm_card_new is called. For the CVSS the PR:L is used in the paranoid view because a reduced admin service or delegated device management context may be enough to reach the sysfs bind path in some deployments. The issue is not network reachable and requires local control of driver binding or an equivalent device management interface. Impact is at least denial of service via kernel crash, with limited confidentiality impact possible from OOB reads, but no supported OOB write or privilege escalation primitive is visible from the patch context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended (with actual score 2) YES OOB SIMPLEFIX HARDWARE LINUS SYZBOT DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=1
## 1. ActionableScore
* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Borderline manual review recommended**::
## 2. Signal breakdown
Conservative signals:
* Weak/indirect corruption candidate: +1. `snd_dummy_probe()` uses `devptr->id` as an array index for `index[dev]`, `id[dev]`, and likely related module parameter arrays without range validation.
* Reliable crash / availability concern: +1. The OOB access is in kernel probe code and can plausibly lead to an invalid pointer or invalid parameter use during `snd_devm_card_new()`.
* Requires admin/root/device-management access in typical deployments: -2. Manual driver binding through sysfs normally requires privileged local access.
* Availability impact realistic: +1. A bad probe path can crash or destabilize the kernel or driver state.
Paranoid additional interpretation:
* Confidentiality impact plausible: +1. The primitive is read-side OOB array access, so limited kernel data disclosure or use of adjacent values is theoretically possible, although no direct leak path is shown.
* Privileged kernel/device-management memory corruption path: +1. The bug occurs during manual driver binding and device probe, where invalid kernel object configuration can affect trusted driver initialization.
* Rare and difficult-to-reach path: -1. `snd_dummy` plus manual sysfs bind is not a broad default attack surface.
No strong LPE signal is awarded. No OOB write, UAF reclaim, callback control, type confusion, refcount takeover, or arbitrary write primitive is shown.
## 3. Reachability analysis
The bug is local only. It is not network reachable. The realistic trigger is manual binding of the ALSA dummy platform driver through sysfs with an invalid platform device id such as `-1`. In normal deployments this requires root or equivalent device-management privileges. A paranoid PR:L interpretation is possible only in environments where a reduced admin service, container root with delegated device control, or another limited management context can reach the sysfs bind path. The affected path is not a common default user data path.
Call-site confidence: high. The patch directly shows the unchecked index and the immediate use in `snd_devm_card_new()`.
## 4. Severity interpretation
This behaves more like a low-to-borderline Moderate kernel memory safety issue than an Important vulnerability. The theoretical risk is an OOB read in kernel code with possible crash and limited confidentiality concern. The realistic evidence supports local privileged DoS, not privilege escalation. Manual review is still justified because OOB access in probe code can sometimes have subsystem-specific side effects that are not obvious from the small diff.
## 5. One-sentence report phrase
ALSA dummy driver probe used an unvalidated platform device id as an array index, allowing a local actor with device binding control to trigger OOB reads and possible kernel crash, with limited confidentiality concern but no demonstrated privilege escalation primitive.
## 6. Manual review recommendation
MANUAL CHECK RECOMMENDED. YES REQUIRES MANUAL CHECK.
Reason: this is kernel OOB access reported by syzbot, but the trigger appears privileged and no write primitive or practical LPE path is visible from the patch.
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: ALSA: dummy: Check card index validity at probe
Commit: b7579e86afcec932e169d10e2d603abed8dd2fdf
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b7579e86afcec932e169d10e2d603abed8dd2fdf
Commit description:
snd_dummy_probe() blindly trusts that the given devptr->id value is
within the proper card index range. 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.
Reported-by: [email protected]
Closes: https://lore.kernel.org/[email protected]
Cc: <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
sound/drivers/dummy.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=b7579e86afcec932e169d10e2d603abed8dd2fdf
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80812 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80812
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:N/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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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