[CVE-2026-74411][MODERATE REGULAR] wifi: rtw89: Correct data type for scan index to avoid infinite loop [ Upstream

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

CVE: CVE-2026-74411
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: rtw89: Correct data type for scan index to avoid infinite loop [ Upstream
Commit: 966fbed4b4463fbcb49c5becf3f86eae776861bd
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=966fbed4b4463fbcb49c5becf3f86eae776861bd
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74411
Analysis date: Sat, 15 Aug 2026 13:01:32 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline Moderate, manual review recommended
Manual review required: YES

Summary:
A u8 loop counter in the rtw89 6 GHz scan path can wrap when processing more than 255 scan parameters, causing an infinite loop, CPU soft lockup, and possible kernel panic on affected Wi-Fi systems.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-74411 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74411

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-74411	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';CWE-190;*CWE-835;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.3';DESCR 'A scan index wraparound in the rtw89 6 GHz scan path can cause an infinite loop when the number of 6 GHz scan parameters exceeds 255. The loop counter was stored in an 8 bit type, so it can wrap and keep revalidating values instead of reaching the real limit. This can result in a CPU soft lockup in rtw89_hw_scan_add_chan_ax and may lead to a kernel panic, causing denial of service. For the CVSS the PR:N is used in the paranoid adjacent attack model because a nearby attacker controlling crafted Wi-Fi beacon or RNR data may not need local privileges on the victim if the victim performs 6 GHz scanning. The issue is adjacent network reachable rather than Internet reachable and exploitation depends on a suitable Wi-Fi environment with enough scan parameters. Impact is availability only, with no supported evidence of memory corruption, information disclosure, or privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Moderate, manual review recommended (with actual score 3)	YES	REMOTE DEADLOCK DANGER NETWORK KERNEL_PANIC_PLUS_UAF HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline Moderate, manual review recommended**

## 2. Signal breakdown

* Adjacent network-triggerable / wireless external influence: +2 in paranoid scoring. A nearby attacker may be able to influence 6 GHz RNR or scan parameters through Wi-Fi management-frame environment, but this is adjacent RF exposure, not Internet-reachable.
* Local unprivileged trigger: +1 in conservative scoring. A local user or desktop network service may initiate Wi-Fi scanning, depending on policy and user permissions.
* Reliable kernel crash / strong DoS: +1. The commit shows a reproducible CPU soft lockup lasting more than 20 seconds and leading to panic.
* Hard or special triggering conditions: -1. Triggering requires 6 GHz scan state with more than 255 parameters and likely a specific RF/device environment.
* No memory corruption signal: +0. The patch only changes the loop counter type from u8 to u32. It supports integer wraparound and infinite loop, not UAF, OOB write, type confusion, or LPE.
* Availability impact realistic: +0 additional. Crash impact is already counted as strong DoS, and there is no persistent corruption or broader availability effect beyond panic.
* Driver and hardware specificity: conservative downgrade considered. rtw89 is hardware-specific, but Wi-Fi scanning is a common user-visible path, so I do not apply a strong rare-subsystem penalty.

## 3. Reachability analysis

A local user may be able to trigger scanning directly or indirectly through normal Wi-Fi management components, depending on distro policy and NetworkManager or wpa_supplicant integration. A nearby attacker may be able to influence the scan input indirectly through crafted or dense 6 GHz RNR information, but this requires adjacent wireless presence and a compatible rtw89 device. Containers do not materially improve reachability unless they can access host Wi-Fi control paths. The affected path is not Internet-reachable and is limited to systems using the Realtek rtw89 driver with 6 GHz scan support.

## 4. Severity interpretation

This behaves like an actionable DoS-oriented Moderate, not an Important memory-corruption issue. The realistic impact is kernel soft lockup and panic. Theoretical LPE is not supported by the patch because the fix addresses an integer-width loop counter bug, with no evidence of stale object reuse, overwrite, UAF, or attacker-controlled kernel memory corruption.

## 5. One-sentence report phrase

A u8 loop counter in the rtw89 6 GHz scan path can wrap when processing more than 255 scan parameters, causing an infinite loop, CPU soft lockup, and possible kernel panic on affected Wi-Fi systems.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: no memory corruption or LPE is indicated, but the bug is plausibly adjacent-wireless-triggerable and causes kernel panic, so it should not be auto-closed without confirming real-world 6 GHz RNR triggerability and affected product exposure.

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

Patch: wifi: rtw89: Correct data type for scan index to avoid infinite loop [ Upstream
Commit: 966fbed4b4463fbcb49c5becf3f86eae776861bd
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=966fbed4b4463fbcb49c5becf3f86eae776861bd

Changed files:
  drivers/net/wireless/realtek/rtw89/fw.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=966fbed4b4463fbcb49c5becf3f86eae776861bd

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

The original Linux kernel CVE announcement for CVE-2026-74411 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74411

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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.3

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