* [CVE-2026-98308][LOW] ALSA: hda: trace PCM open only after assigning a stream [ Upstream
@ 2026-10-11 5:05 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-11 5:05 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98308
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: ALSA: hda: trace PCM open only after assigning a stream [ Upstream
Commit: 5a4c974dee03cc46eac43c82f33e34ec94f0b348
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5a4c974dee03cc46eac43c82f33e34ec94f0b348
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98308
Analysis date: Sun, 11 Oct 2026 01:05:53 -0400
ActionableScore: 1
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-2026-98308 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98308
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: LOW
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-2026-98308 LOW https://www.kernelcve.org/list/?q=CVE-2026-98308 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=0 LEGACY=LOW RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both 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:N/A:H';**CWE-476;CWE-754;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A NULL pointer dereference can occur in the ALSA HDA PCM open path because trace_azx_pcm_open may access the stream tag before azx_assign_device is checked for failure. A local user with access to the PCM device may reach the failing path when all hardware streams are exhausted, but the vulnerable tracepoint normally also needs to be enabled. The resulting invalid read can cause a kernel Oops or a system crash when panic on Oops is enabled. For the CVSS the PR:L value is used because a local process with permission to open the ALSA PCM device is required, while administrative control of the system is not necessarily required for the triggering process. The issue is not network reachable. Impact is denial of service only because the code shows a NULL dereference and provides no UAF, out of bounds write, information leak, or arbitrary write primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE SIMPLEFIX HARDWARE LINUS INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Local below-host-admin trigger. A process with permission to open the ALSA PCM device can reach `azx_pcm_open()` and may encounter stream-assignment failure when hardware streams are exhausted.
* +1 Kernel fault or DoS. With the tracepoint enabled, its payload dereferences the NULL `azx_dev`, potentially producing a kernel Oops or panic under `panic_on_oops`.
* -1 Rare and attacker-uncontrollable prerequisite. The affected tracepoint must normally be enabled through privileged tracing controls. An ordinary PCM client cannot establish this prerequisite itself.
* No UAF, OOB access, heap overwrite, repeated release, refcount mutation, shared-backing write, or authorization bypass is established.
* No extra availability point is awarded because Oops and panic are the same underlying fault.
* No confidentiality or integrity signal is awarded. The invalid access is a NULL dereference without a disclosure or write primitive.
* B5-R does not apply because there is no retry-accumulated heap OOB write or later consumption of corrupted structured state.
* B3-PENDING does not apply because no shared or file-backed storage is modified.
* B4-PENDING does not apply because no DENY-to-ALLOW authorization decision changes.
3. Reachability analysis
The vulnerable operation is a local ALSA PCM open. A non-root desktop or audio-service process may have device-file permission, so the triggering process itself need not possess host-administrator powers or UID 0. The path is not namespace-capability based and is not network reachable.
The important prerequisite is that `trace_azx_pcm_open` must be enabled for its payload to execute. Enabling kernel tracing normally requires a separately privileged actor, and the PCM client cannot ordinarily enable it. No special race is required. The failure occurs when `azx_assign_device()` returns NULL after hardware streams are exhausted. Common HDA hardware is involved, but no rare-hardware penalty is applied separately because the tracing prerequisite already captures the material exposure restriction.
4. Primitive and severity interpretation
The exact primitive is a conditional NULL-pointer dereference in a tracepoint payload. This is Class C invalid-state and crash behavior, not a lifetime violation or memory-corruption primitive.
There is no freed object, stale storage, repeated release, corrupted descriptor, attacker-selected destination, or post-corruption structured-state consumption. The demonstrated consequence is an Oops or possible host crash. Privilege escalation, information disclosure, and integrity modification are unsupported.
`ImportantCandidate=NO` because no Important-preserving primitive is present. `AutoDowngradeAllowed=YES` because the issue is a configuration-dependent local NULL dereference with no unresolved corruption or authorization boundary.
5. One-sentence report phrase
A locally reachable ALSA HDA tracepoint can dereference a NULL stream after hardware stream exhaustion when tracing is enabled, causing an Oops or conditional kernel panic without a demonstrated memory-corruption or privilege-escalation primitive.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
The patch establishes a narrow NULL-dereference DoS with a privileged tracing prerequisite and no UAF, OOB write, authorization bypass, or unresolved integrity primitive.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: ALSA: hda: trace PCM open only after assigning a stream [ Upstream
Commit: 5a4c974dee03cc46eac43c82f33e34ec94f0b348
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5a4c974dee03cc46eac43c82f33e34ec94f0b348
Changed files:
sound/pci/hda/hda_controller.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=5a4c974dee03cc46eac43c82f33e34ec94f0b348
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98308 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98308
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:N/I:N/A:H
The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 5.5
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: 1
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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW
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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