* [CVE-2026-97966][MODERATE REGULAR] octeontx2-pf: reset HTB scheduler topology before freeing queues [ Upstream
@ 2026-09-25 15:12 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-25 15:12 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-97966
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: octeontx2-pf: reset HTB scheduler topology before freeing queues [ Upstream
Commit: 0aa2dd6eaa347c7aab448df0eec0afcfe7489885
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0aa2dd6eaa347c7aab448df0eec0afcfe7489885
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97966
Analysis date: Fri, 25 Sep 2026 11:12:28 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-97966 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97966
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-2026-97966 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-97966 CHECK WITH IMPACT FROM ORIG NN MODERATE 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-665;CWE-668;CWE-284;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '5.8';DESCR 'A stale hardware scheduler topology can survive HTB QoS hierarchy teardown because freed TL4 through TL2 scheduler queues are returned to the shared AF pool without clearing their TOPOLOGY registers. A later allocation can inherit PRIO_ANCHOR or RR_PRIO settings from a previous owner and may receive unexpected traffic scheduling behavior, causing QoS policy bypass or traffic degradation. For the CVSS the PR:L paranoid score applies when a tenant, container root, or service account has delegated CAP_NET_ADMIN access to configure HTB offload on an assigned interface. The issue is not directly network reachable and requires local control plane QoS operations, queue release, and reuse of affected hardware resources. Impact is primarily availability and integrity of traffic scheduling. No memory corruption, direct kernel crash, or proven privilege escalation primitive is shown by the patch.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) YES REMOTE LOCK INIT NOMEMCHK UAF NETWORK LOG LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 YES NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 3
* Paranoid score: 3
* Final recommended bucket: **Borderline / manual review recommended**::
No floor or cap was applied.
2. Signal breakdown
Conservative signals:
* +1 Active hardware state retirement failure. Scheduler queues are returned to the AF shared pool while TL4 through TL2 TOPOLOGY state remains programmed. The normal queue release operation restores PARENT and SCHEDULE but not TOPOLOGY.
* +1 Persistent cross-allocation configuration effect. The patch explicitly states that PRIO_ANCHOR and RR_PRIO settings can survive queue release and affect a later allocation from the shared scheduler pool.
Paranoid-only signal:
* +1 Potential QoS isolation or policy interference. If the stale queue is subsequently allocated to a different PF, VF, tenant, or delegated network-management context, prior scheduling topology can influence another allocation and degrade expected QoS separation.
Non-awarded material signals:
* No concrete UAF, double release, refcount corruption, OOB access, arbitrary write, or controlled kernel-memory corruption is established.
* No kernel crash, host-wide DoS, device reset loop, or reliable availability failure is established.
* No remote reachability is established. This is a local QoS control-plane configuration path.
* No confidentiality impact is established.
* No direct integrity impact on protected kernel memory, credentials, files, or another principals data is established.
* No privilege escalation or authorization bypass is established.
* No strong semantic reinterpretation primitive is established. The bug preserves stale hardware scheduler configuration, but does not reinterpret attacker-controlled bytes as active kernel pointers, ownership objects, or executable operations.
* No privilege penalty was applied because host-admin-equivalent privilege is not positively established from the supplied patch. CAP_NET_ADMIN may be relevant, but the applicable namespace and complete trigger chain are unresolved.
3. Reachability analysis
The trigger requires configuring HTB hardware offload on an OcteonTX2 PF, tearing down or rolling back the QoS hierarchy, and causing reuse of scheduler queues whose TOPOLOGY registers were not reset. The affected state is programmed through the driver mailbox into NIX AF scheduler hardware.
The likely attacker is a local network-management actor that can configure traffic control and HTB offload on the affected interface. The supplied evidence does not establish whether this requires host init_user_ns CAP_NET_ADMIN, whether it can be performed by a delegated service account, or whether a tenant or VF can complete the full configuration, teardown, and scheduler-reuse sequence.
NamespaceScopedPrivilege is UNKNOWN. A namespace-local CAP_NET_ADMIN capability may permit some rtnetlink or qdisc operations, but the complete path also depends on hardware offload support, the physical PF, firmware AF resource allocation, and scheduler queue reuse. The patch does not show that all required operations are available in an attacker-created namespace.
Special hardware is required. The path is specific to Marvell OcteonTX2 hardware with HTB offload support enabled and actively used. However, no rare-hardware penalty was applied because the supplied context does not establish that the device is inaccessible to the evaluated attacker or that the vulnerability is limited to physical-only access.
The sequence is not a timing race. It requires an ordered configuration, teardown, and later allocation sequence. Queue reuse may require repeated attempts or resource pressure, but the supplied patch does not establish a narrow or externally uncontrollable timing window.
4. Primitive and severity interpretation
The exact primitive is stale hardware scheduler topology state. A TL4 through TL2 scheduler queue is released into a shared AF pool without clearing its TOPOLOGY register. A later allocation can inherit PRIO_ANCHOR or RR_PRIO configuration that belonged to the prior allocation.
This is not a memory-lifetime defect. No object is freed while a stale pointer remains dereferenced, so RealUAF is NO. There is no repeated put, refcount mutation, DMA access to freed memory, controlled reclaim, callback use, or active kernel-object type confusion.
The affected resource is active hardware scheduling state rather than fixed stale storage. The observable practical effect is unexpected packet scheduling behavior, QoS policy interference, or traffic degradation for a later queue allocation. The patch does not demonstrate that the later allocation belongs to a distinct security principal, that an untrusted VF can trigger the full sequence, or that stale configuration yields direct cross-tenant traffic manipulation.
PrimitiveClass is CLASS_C because the demonstrated issue is invalid persistent device state and possible QoS misconfiguration rather than kernel corruption, lifetime corruption, or a concrete authorization bypass. ImportantCandidate is NO because no meaningful exploitation primitive beyond configuration-state contamination is established. AutoDowngradeAllowed is YES because the current evidence supports a constrained policy and scheduling issue without demonstrated memory corruption, protected-resource access, or a proven cross-boundary security consequence.
The paranoid score preserves a small additional concern for cross-allocation QoS isolation. It does not assume privilege escalation, packet disclosure, arbitrary traffic injection, or host compromise.
5. One-sentence report phrase
Stale HTB scheduler TOPOLOGY state can survive OcteonTX2 queue release and affect later shared scheduler allocations, potentially causing QoS policy interference or traffic degradation.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Confirm whether untrusted VFs, delegated CAP_NET_ADMIN service accounts, or containerized network-management actors can configure HTB offload and later obtain scheduler queues previously released by another security context.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: octeontx2-pf: reset HTB scheduler topology before freeing queues [ Upstream
Commit: 0aa2dd6eaa347c7aab448df0eec0afcfe7489885
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0aa2dd6eaa347c7aab448df0eec0afcfe7489885
Changed files:
drivers/net/ethernet/marvell/octeontx2/nic/qos.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=0aa2dd6eaa347c7aab448df0eec0afcfe7489885
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-97966 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97966
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:H/UI:N/S:U/C:N/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: 2
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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