[CVE-2026-98887][MODERATE REGULAR] wifi: mac80211_hwsim: reject undersized HWSIM_ATTR_TX_INFO [ Upstream

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-98887
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: mac80211_hwsim: reject undersized HWSIM_ATTR_TX_INFO [ Upstream
Commit: 3a96bb65b4b820d8b41fa155781ec1c29e3479d4
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3a96bb65b4b820d8b41fa155781ec1c29e3479d4
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98887
Analysis date: Tue, 27 Oct 2026 01:50:17 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A malformed local hwsim TX-info attribute causes a bounded eight-byte kernel OOB read with possible crash impact but no shown disclosure, write, or privilege-boundary effect.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98887 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98887

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.

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AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-98887	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98887 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (final Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC)	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-125;*CWE-20;CWE-1284;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'mac80211_hwsim accepts an undersized HWSIM_ATTR_TX_INFO because the NLA_BINARY length was only a maximum and strict validation is disabled for the operation. hwsim_tx_info_frame_received_nl then treats the payload as a complete rate array and performs a bounded 8 byte out of bounds read relative to the attribute. For the CVSS the PR:L value reflects that a local process with access to the hwsim control path and normally the registered wmediumd role is needed for reliable triggering. The issue is not directly network reachable. No OOB write, UAF, information return path, or demonstrated privilege escalation is present. The paranoid vector allows high availability impact if the invalid read causes a kernel fault or a diagnostic failure is converted into panic, while confidentiality and integrity remain none. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 5.5 and the production ActionableScore returned 2 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. 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_CIANNH and V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 0.0 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	MAYBE	REMOTE VIRT SIMPLEFIX NETWORK  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED	-	-	checked

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ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 1.
* Conservative score: 1; no floor or cap applied.
* Raw paranoid score: 2.
* Paranoid score: 2; no floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 weak read-only OOB primitive: an undersized or empty binary attribute is cast to `struct hwsim_tx_rate *`, followed by a fixed eight-byte read beyond the attribute payload.
* -1 reduced-role prerequisite: supplied evidence indicates that reliable triggering normally requires access to the hwsim control path and the registered wmediumd role, rather than an ordinary local interface.
* +1 paranoid crash concern: the invalid read could plausibly fault if it crosses accessible skb/storage bounds. This is not a confirmed or reliable panic.
* No OOB write, stale lifetime use, disclosure path, attacker-controlled write, authorization bypass, or integrity effect is shown.
* NEW52/B5-R does not apply: there is no write, retry-accumulated index, or later consumption of corrupted state.
* No extra availability point is awarded for the same possible fault.

3. Reachability analysis

The path is local generic-netlink control traffic, not direct wireless or remote packet reachability. The supplied summary grounds access through a low-privilege hwsim/wmediumd role, supporting below-host-admin reachability, but it does not establish whether host UID 0 is required or whether the complete operation is available within attacker-created user/net namespaces. No race, retry sequence, special hardware, or remote trigger is required.

4. Primitive and severity reading

The exact primitive is a fixed-size read past a short netlink attribute. It is read-only and likely remains within surrounding skb allocation in many executions, but harmless containment is not proven. The shown impact is malformed internal rate data consumption; a kernel fault is plausible but not demonstrated. There is no read-back to userspace, write primitive, UAF, protected-state change, or authorization decision bypass. This is therefore CLASS_C, not an Important-preserving corruption candidate, and automatic Moderate downgrade is allowed.

5. One-sentence report phrase

A malformed local hwsim TX-info attribute causes a bounded eight-byte kernel OOB read with possible crash impact but no shown disclosure, write, or privilege-boundary effect.

6. Manual review advice

MANUAL CHECK RECOMMENDED

Confirm actual generic-netlink permissions and whether the read can cross the skb allocation boundary on supported configurations.

7. Call-site confidence

Call-site confidence: medium

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: wifi: mac80211_hwsim: reject undersized HWSIM_ATTR_TX_INFO [ Upstream
Commit: 3a96bb65b4b820d8b41fa155781ec1c29e3479d4
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3a96bb65b4b820d8b41fa155781ec1c29e3479d4

Changed files:
  drivers/net/wireless/mac80211_hwsim.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=3a96bb65b4b820d8b41fa155781ec1c29e3479d4

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98887 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98887

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: 1
  Paranoid ActionableScore: 2

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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).