* [CVE-2026-98585][MODERATE REGULAR] eth: fbnic: Avoid rounding zero ring sizes [ Upstream
@ 2026-10-24 17:12 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-24 17:12 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98585
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: eth: fbnic: Avoid rounding zero ring sizes [ Upstream
Commit: 92c9f2ea634d92adff5403d231ebeda683c5685a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=92c9f2ea634d92adff5403d231ebeda683c5685a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98585
Analysis date: Sat, 24 Oct 2026 13:12:01 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
A privileged ethtool request can pass zero to undefined ring-size rounding, but the patch shows no concrete memory corruption or reliable kernel failure.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98585 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98585
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-2026-98585 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98585 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE AEGIS_AS=0 LEGACY=MODERATE RESULT=SAME V39_AEGIS_ONE_STEP_UP=LOW->MODERATE (final reconciliation agrees; DECISION: both MODERATE) 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:L';CWE-190;CWE-682;CWE-758;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '3.3';DESCR 'The fbnic ethtool ring configuration path passed a zero ring size to roundup_pow_of_two before applying the minimum size check. roundup_pow_of_two is undefined for zero and can produce an architecture or compiler dependent result or a diagnostic warning, but the available evidence does not establish an OOB access, UAF, information leak, arbitrary write, or reliable kernel crash. The issue is local and requires control of an ethtool ring configuration request for an affected FBNIC device. For the CVSS the PR:L value in the paranoid vector reflects deployments where network device administration is delegated to a restricted service, container, or network administrator. Normal host configuration usually requires CAP_NET_ADMIN and supports PR:H. Confidentiality and integrity remain unaffected, while availability impact is low because the demonstrated failure is limited to undefined ring size calculation and rejection behavior. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 3.3 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to MODERATE because KP specialist did not establish a qualifying panic and the cross model evidence reconciliation 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 DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 0.0 and ActionableScore 0 with primitive class NONE and manual review REQUIRED. Its independently reconciled impact was MODERATE. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) MAYBE REMOTE SIMPLEFIX NETWORK HARDWARE LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw base score: 0.
* Conservative score: 0; no floor or cap applies.
* Raw paranoid score: 0.
* Paranoid score: 0; undefined zero-input arithmetic alone does not establish a crash or corruption primitive.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +0: A zero ring size reaches `roundup_pow_of_two(0)`, whose result is undefined, but the subsequent minimum-size validation is intended to reject zero.
* +0: No confirmed OOB access, heap write, UAF, disclosure, authorization bypass, or reliable kernel crash is shown.
* +0: NEW52/B5-R does not apply: there is no retry-accumulated index, confirmed OOB write, or later consumption of corrupted structured state.
* +0: No reliable DoS point; the evidence supports architecture/compiler-dependent calculation or diagnostics, not a demonstrated fatal fault.
* No privilege penalty applied because effective host-admin requirements and capability namespace scope are not conclusively established.
3. Reachability analysis
The input is an ethtool ring-configuration request for an affected FBNIC device. Such configuration requires network-device administrative authority, ordinarily CAP_NET_ADMIN, but the supplied evidence does not resolve whether the complete operation can be delegated below host-admin or performed entirely with namespace-scoped capability. Numeric host UID 0 is not inherently required. An affected device must exist; no race, retry sequence, or special timing is involved.
4. Primitive and severity reading
The defect is invalid zero-input handling before a deterministic minimum-size rejection. It does not show memory corruption, stale lifetime use, active structured-state corruption, or an authorization decision changing from DENY to ALLOW. Any kernel crash or downstream ring corruption is speculative. Therefore the primitive class is NONE, there is no Important candidate, and automatic downgrade is allowed.
5. One-sentence report phrase
A privileged ethtool request can pass zero to undefined ring-size rounding, but the patch shows no concrete memory corruption or reliable kernel failure.
6. Manual review advice
NO MANUAL CHECK NEEDED
The patch establishes defensive validation ordering without a material security primitive.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: eth: fbnic: Avoid rounding zero ring sizes [ Upstream
Commit: 92c9f2ea634d92adff5403d231ebeda683c5685a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=92c9f2ea634d92adff5403d231ebeda683c5685a
Changed files:
drivers/net/ethernet/meta/fbnic/fbnic_ethtool.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=92c9f2ea634d92adff5403d231ebeda683c5685a
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98585 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98585
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:L
The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
The Best / paranoid CVSS score: 3.3
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: 0
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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