[CVE-2026-74323][MODERATE REGULAR] wifi: mt76: mt7996: Fix possible token leak in mt7996_tx_prepare_skb() [ Upstream

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

CVE: CVE-2026-74323
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: mt76: mt7996: Fix possible token leak in mt7996_tx_prepare_skb() [ Upstream
Commit: 06e65d6cf80490bc0457d339595d1ed5a89e8899
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=06e65d6cf80490bc0457d339595d1ed5a89e8899
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74323
Analysis date: Sat, 15 Aug 2026 23:25:12 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline Moderate. Manual review recommended due to adjacent network token exhaustion possibility
Manual review required: YES

Summary:
A TX token leak in mt7996_tx_prepare_skb() can occur when link_conf or link_sta lookup fails after token allocation, allowing repeated failures to exhaust the driver token pool and cause adjacent-network denial of service on affected mt7996 WiFi devices.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-74323 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74323

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-2026-74323	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-772;*CWE-401;**CWE-400;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'A TX token leak in the mt76 mt7996 transmit path can occur when mt7996_tx_prepare_skb() allocates a token and then fails the link_conf or link_sta lookup. Repeated failures can exhaust the driver token pool and degrade or block wireless transmission for the affected mt7996 device. For the CVSS the PR:N is used because a nearby wireless attacker may not need local privileges on the target host, but reliable triggering appears to depend on specific WiFi state, MLO or EAPOL related handling, and mt7996 hardware. The issue is adjacent network reachable rather than Internet reachable because the attacker must be within WiFi range or otherwise able to interact with the wireless link. Impact is denial of service only through resource exhaustion. There is no supported UAF, OOB access, arbitrary write, information disclosure, or privilege escalation primitive in this patch context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Moderate. Manual review recommended due to adjacent network token exhaustion possibility (with actual score 3)	YES	REMOTE OOB INIT SIMPLEFIX LEAK NETWORK MEMORY  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	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 due to adjacent network token exhaustion possibility**

## 2. Signal breakdown

* Remote reachable / network-triggerable: +2 in paranoid interpretation. A nearby wireless peer may influence the mt7996 transmit path through WiFi traffic or association related state, but this is adjacent network rather than Internet reachable.
* Availability impact realistic: +1. Repeated token leaks can exhaust the TX token pool and degrade or block wireless transmission for the affected device.
* Hard or unreliable trigger / special state required: -1. The leak requires failure of link_conf or link_sta lookup after token allocation, likely depending on MLO/EAPOL state transitions or teardown timing.
* Rare hardware / device specific condition: -1. The issue is specific to the MediaTek mt7996 driver and affected runtime configuration.

No memory corruption, UAF, OOB access, arbitrary write, information leak, or privilege escalation primitive is supported by the patch.

## 3. Reachability analysis

A local user is not necessarily required if the failing path can be reached through WiFi peer behavior, but reliable triggering is not proven from the patch alone. The realistic attacker is adjacent to the wireless network or otherwise able to interact with the mt7996 AP/client link. Namespaces and containers do not materially change reachability because the vulnerable path is in the device transmit path, not a local namespace control API. The path is only relevant on systems using mt7996 hardware and the affected MLD/EAPOL related code.

Call-site confidence: medium. The changed function and release helper are visible, and the resource lifetime error is clear, but the exact external triggerability of link_conf or link_sta lookup failure is not fully demonstrated.

## 4. Severity interpretation

This behaves like an actionable resource-exhaustion Moderate rather than an Important-class kernel memory corruption issue. The theoretical worst case is sustained TX token exhaustion causing wireless DoS on the affected device. Realistic exploitation evidence is weaker because the patch does not show a simple attacker-controlled trigger and does not provide a crash, UAF, write primitive, or privilege escalation path.

## 5. One-sentence report phrase

A TX token leak in mt7996_tx_prepare_skb() can occur when link_conf or link_sta lookup fails after token allocation, allowing repeated failures to exhaust the driver token pool and cause adjacent-network denial of service on affected mt7996 WiFi devices.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: adjacent-network reachability and repeatability of token exhaustion should be verified manually, but the patch supports DoS-only impact and does not justify Important severity.

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

Patch: wifi: mt76: mt7996: Fix possible token leak in mt7996_tx_prepare_skb() [ Upstream
Commit: 06e65d6cf80490bc0457d339595d1ed5a89e8899
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=06e65d6cf80490bc0457d339595d1ed5a89e8899

Changed files:
  drivers/net/wireless/mediatek/mt76/mt7996/mac.c
  drivers/net/wireless/mediatek/mt76/tx.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=06e65d6cf80490bc0457d339595d1ed5a89e8899

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

The original Linux kernel CVE announcement for CVE-2026-74323 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74323

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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
  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).