[CVE-2026-74408][MODERATE 7.0] wifi: ath9k: fix OOB access from firmware tx status queue ID [ Upstream

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

CVE: CVE-2026-74408
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: ath9k: fix OOB access from firmware tx status queue ID [ Upstream
Commit: fb11083db9d7d6fb8f98bbba1cbfcf3fb7b4bf54
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fb11083db9d7d6fb8f98bbba1cbfcf3fb7b4bf54
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74408
Analysis date: Sun, 16 Aug 2026 03:22:12 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
An unchecked firmware TX status queue ID in ath9k can index past the sc->tx.txq array and use adjacent memory as a TX queue object, causing a kernel crash and possible driver state corruption under firmware or hardware influenced conditions.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-74408 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74408

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 7.0
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-2026-74408	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:H/I:H/A:H';CWE-129;*CWE-787;CWE-125;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.5';DESCR 'ath9k uses ts.qid from a firmware TX status field as an index into sc->tx.txq, but the hardware field can encode values 0 to 15 while the txq array has only 10 entries. A qid value of 10 or higher can make ath_tx_edma_tasklet access memory outside the array and then use the resulting pointer as a TX queue object, which can lead to kernel crash and potentially memory corruption. For the CVSS the PR:N is used in the paranoid adjacent-network interpretation because a WiFi radio neighbor may not need a local account if the invalid TX status can be induced through wireless interactions with an exposed ath9k interface. The base case is more conservative and treats reliable triggering as local and high complexity because the invalid qid originates from firmware or hardware status rather than directly from packet bytes. Impact is at least denial of service and in worst case may allow confidentiality or integrity impact due to out-of-bounds access in kernel driver state. YES REQUIRES MANUAL CHECK.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	REMOTE OOB SIMPLEFIX NETWORK HARDWARE  INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN6 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**

## 2. Signal breakdown

Conservative signals:

* +1 Firmware-mediated external influence. The invalid qid comes from a hardware or firmware TX status field, not directly from a normal userspace argument.
* +1 Memory corruption, weak or indirect corruption candidate. ts.qid is used as an unchecked array index into sc->tx.txq, producing a bogus txq object pointer for qid 10 to 15.
* +1 Reliable kernel crash / strong DoS. The bogus txq pointer is passed into queue locking and TX handling, making kernel crash realistic.
* +1 Privileged kernel/device-management memory corruption path. The corruption occurs inside a trusted WiFi driver TX completion/tasklet path using firmware-fed metadata.
* -1 Hard or unreliable trigger. The attacker control over ts.qid is not demonstrated and likely depends on device, firmware, traffic timing, or malformed hardware status behavior.

Paranoid additional signals:

* +1 Weak LPE concern. The bug involves bogus object selection and later use as a kernel TX queue object, but no reclaim, arbitrary write, or controlled payload is shown.
* +1 Integrity impact plausible. OOB use of a fake txq may result in writes to adjacent kernel driver state through locking or queue operations.
* Confidentiality is not counted in the main paranoid score because no read-back or information disclosure path is shown.

Not awarded:

* No +2 remote reachable. Adjacent WiFi influence is possible, but direct network control over the firmware qid is not proven.
* No +2 strong memory corruption primitive. The patch shows OOB object selection, but not attacker-controlled overwrite, UAF reclaim, type confusion, or arbitrary write.
* No Dirty-Pipe-like or page-cache signal.

## 3. Reachability analysis

The affected path is ath9k EDMA TX completion handling. A local user may influence TX activity by generating WiFi traffic, but the invalid qid itself originates from firmware or hardware TX status. A nearby WiFi attacker might influence TX behavior indirectly, so firmware-mediated external influence is reasonable, while full remote network-triggerability is not proven.

Namespaces and containers do not obviously lower the privilege requirement unless the container can access or drive the physical ath9k interface. The path is default only on systems using affected ath9k hardware and EDMA-capable operation, so exposure is hardware-dependent but not merely a debug or rare kernel configuration path.

Call-site confidence: high. The patch context shows the unchecked index and immediate use of the derived txq pointer.

## 4. Severity interpretation

This is more than an ordinary Moderate correctness issue because it is an OOB access in a kernel WiFi driver using firmware-fed state and the resulting pointer is used as a real queue object. Realistic exploitation evidence currently supports kernel crash or driver state corruption more strongly than privilege escalation. Theoretical LPE cannot be excluded because the OOB pointer may lead to writes into adjacent kernel memory, but the patch does not show a controlled overwrite, reclaim primitive, callback control, or arbitrary read/write.

Overall this should be handled as Actionable Moderate at minimum, with manual review to determine whether specific ath9k layouts make the OOB txq use exploitable beyond DoS.

## 5. One-sentence report phrase

An unchecked firmware TX status queue ID in ath9k can index past the sc->tx.txq array and use adjacent memory as a TX queue object, causing a kernel crash and possible driver state corruption under firmware or hardware influenced conditions.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a concrete kernel OOB access followed by use of the derived object pointer in a WiFi driver tasklet path. The available patch supports DoS and weak corruption, but exploitability beyond crash depends on ath9k structure layout, adjacent fields, and whether a local or adjacent attacker can reliably induce qid values 10 to 15.

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UPSTREAM PATCH SUMMARY
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Patch: wifi: ath9k: fix OOB access from firmware tx status queue ID [ Upstream
Commit: fb11083db9d7d6fb8f98bbba1cbfcf3fb7b4bf54
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fb11083db9d7d6fb8f98bbba1cbfcf3fb7b4bf54

Changed files:
  drivers/net/wireless/ath/ath9k/xmit.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=fb11083db9d7d6fb8f98bbba1cbfcf3fb7b4bf54

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

The original Linux kernel CVE announcement for CVE-2026-74408 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74408

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:H/I:H/A:H
  The Best / paranoid CVSS score: 7.5

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: 3
  Paranoid ActionableScore: 5

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 7.0

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).