* [CVE-2026-99068][LOW] ALSA: ctxfi: Fix memory leakage when clearing DAO input mappers
@ 2026-10-26 20:14 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-26 20:14 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-99068
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: ALSA: ctxfi: Fix memory leakage when clearing DAO input mappers
Commit: f7dc71c1ce885f5d9f128037ebc75d9c0356e060
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f7dc71c1ce885f5d9f128037ebc75d9c0356e060
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99068
Analysis date: Mon, 26 Oct 2026 16:14:11 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
ALSA ctxfi loses a mapper-array allocation whenever DAO inputs are cleared, permitting persistent kernel-memory leakage if the operation can be repeated.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-99068 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99068
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-2026-99068 LOW https://www.kernelcve.org/list/?q=CVE-2026-99068 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=0 LEGACY=LOW RESULT=SAME (final reconciliation agrees; 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-401;*CWE-772;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'ALSA ctxfi dao_clear_input removed input mapper entries and cleared their pointers lacking freeing the shared mapper allocation, causing persistent kernel memory retention each time the function was reached. The demonstrated primitive is a memory leak rather than UAF, OOB access, or another memory corruption condition. For the CVSS the PR:L value reflects that exploitation requires a local process with permission to use the affected ALSA sound device. A single invocation is unlikely to cause host wide failure, while sustained repetition could eventually degrade availability or exhaust kernel memory on systems using supported Creative X Fi hardware. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 5.5 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage LOW to MODERATE_KPANIC because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE_KPANIC to LOW because the ActionableScore threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE and DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3. The independent weaker Aegis shadow evaluated CVSS 4.3 and ActionableScore 0 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE SIMPLEFIX LEAK 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=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw base 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 Concrete persistent kernel resource/ref leak:** `dao_clear_input()` deletes mapper entries and nulls every stored pointer without freeing the underlying mapper allocation. Afterward normal cleanup cannot recover that allocation. Saving `dao->imappers[start]` and calling `kfree(entry)` directly establishes the omitted release.
* **+0 resource-exhaustion/DoS:** repeated calls accumulate leaked memory, but the supplied source does not establish invocation frequency, practical exhaustion rate, or reliable host-wide failure.
* No UAF, OOB access, stale-object use, overwrite, authorization bypass, protected-state corruption, or confidentiality/integrity effect is shown.
* No hardware penalty: affected Creative X-Fi hardware is required, but the evidence does not establish rare hardware or physical attacker access.
* NEW52/B5-R, B3-PENDING, and B4-PENDING do not apply.
3. Reachability analysis
The vulnerable function belongs to the ctxfi ALSA driver and therefore requires an affected sound device. The legacy summary says a local process with permission to use that ALSA device may exercise the path, but the supplied source contains no ioctl/call-chain evidence proving the complete trigger, repeated reconfiguration ability, or exact device-node permissions. Consequently host-admin and UID-0 requirements remain unknown. No namespace capability governs the shown cleanup operation, and no race or special timing is involved.
4. Primitive and severity reading
The exact primitive is a persistent heap allocation leak caused by losing all mapper-array pointers without `kfree()`. It is not memory corruption or a lifetime use-after-free. The shown consequence is unrecoverable kernel-memory retention per reachable clear cycle; eventual memory pressure is plausible but not demonstrated as reliable host-wide DoS. This is CLASS_C availability behavior, with no Important-grade leverage or unresolved trust-boundary primitive. Auto-downgrade is therefore allowed.
5. One-sentence report phrase
ALSA ctxfi loses a mapper-array allocation whenever DAO inputs are cleared, permitting persistent kernel-memory leakage if the operation can be repeated.
6. Manual review advice
NO MANUAL CHECK NEEDED
The patch proves only a straightforward resource leak without corruption, authorization bypass, or protected-resource impact.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: ALSA: ctxfi: Fix memory leakage when clearing DAO input mappers
Commit: f7dc71c1ce885f5d9f128037ebc75d9c0356e060
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f7dc71c1ce885f5d9f128037ebc75d9c0356e060
Commit description:
Commit e576e78 ("ALSA: ctxfi: Simplify dao_clear_{left,right}_input() functions")
centralized the DAO input mapper clearing logic in
dao_clear_input(), but omitted the kfree() calls.
It removes the mapper entries from the list and sets their pointers
to NULL without freeing the allocated array. This leaks memory each
time dao_clear_input() is called.
Store the base pointer of the allocation before clearing the mapper
entries and free the array after removing entries from the list.
Fixes: e576e78 ("ALSA: ctxfi: Simplify dao_clear_{left,right}_input() functions")
Cc: [email protected]
Signed-off-by: Harin Lee <[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/pci/ctxfi/ctdaio.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=f7dc71c1ce885f5d9f128037ebc75d9c0356e060
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-99068 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99068
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:N/I:N/A:L
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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