[CVE-2026-98706][MODERATE 7.0] wifi: mac80211: drain PS delivery work during station teardown

[CVE-2026-98706][MODERATE 7.0] wifi: mac80211: drain PS delivery work during station teardown

[AL-KERNEL]

CVE: CVE-2026-98706
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: wifi: mac80211: drain PS delivery work during station teardown
Commit: 843d3a1e6f25027ac85f88f67b95d82c67306dee
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=843d3a1e6f25027ac85f88f67b95d82c67306dee
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98706
Analysis date: Sat, 24 Oct 2026 07:32:15 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
An adjacent wireless peer can race mac80211 station teardown so delayed power-save work consumes and modifies driver-visible station state after its required retirement point.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-98706 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98706

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-2026-98706	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98706 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE_KPANIC RESULT=SAME (final reconciliation agrees; DECISION: both MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-362;*CWE-672;*CWE-664;Other CVSS 'AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '6.4';DESCR 'A teardown race in mac80211 allows drv_deliver_wk to continue after the station is marked dead and after driver removal or power save queue cleanup has started. The demonstrated primitive is stale asynchronous work that can invoke driver delivery, wake TXQs, or modify power save accounting after the protected lifetime transition. A concrete UAF or arbitrary write is not proven, but crossing the driver station lifetime boundary leaves a plausible driver specific memory safety and kernel crash risk. For the CVSS the PR:N value in the paranoid vector reflects an adjacent wireless peer on an open or otherwise accessible WLAN that can trigger power save delivery and station teardown without local host privileges, while secured WLANs may require valid association credentials. Automated impact decision path. The original SimpleNet classifier selected MODERATE. The primary LLM estimated paranoid CVSS 6.4 and the production ActionableScore returned 5 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE to IMPORTANT because the CVSS score, vector or bug class threshold rule was applied. KP and FD specialist checks stage IMPORTANT to MODERATE_KPANIC because a specific evidence based protection or manual review veto was applied and FD false positive review allowed a downgrade. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist produced a review artifact and its decision was processed by the applicable downgrade and preservation rules. Exact triggered rule markers were INCREASED_TO_HIGH_BASED_ON_GUESSCVSS and V33_ACTIVE_STATE_BOUNDARY_CANDIDATE and IMPORTANT_CANDIDATE_MANUAL_REVIEW and KP_ONLY_DOWNGRADE_VETO and DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFDH. 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 shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)	MAYBE	REMOTE TEST  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS V33_ACTIVE_STATE_BOUNDARY_CANDIDATE IMPORTANT_CANDIDATE_MANUAL_REVIEW KP_ONLY_DOWNGRADE_VETO DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFDH	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 5.
* Conservative score: 5; no floor or cap applied.
* Raw paranoid score: 5.
* Paranoid score: 5; stronger memory-corruption consequences are not sufficiently proven.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +2 clearly network-reachable: supplied evidence grounds an adjacent wireless station influencing power-save delivery and station teardown without host privileges, at least on an accessible WLAN.
* +1 active structured-state corruption candidate: delayed work can update power-save accounting/queues after purge and invoke driver delivery or TXQ wake operations after station removal.
* +1 active-state retirement/synchronization bypass: cancellation was performed only after the driver-state transition and cleanup it needed to protect; the fix drains work before those transitions.
* +1 plausible kernel crash/strong DoS: post-removal driver callbacks and consumption of purged state can plausibly fault or destabilize the host, although panic is not demonstrated.
* +1 common packet-processing subsystem: mac80211 station power-save delivery is a broadly deployed wireless path.
* -1 hard timing requirement: exploitation requires the worker to pass the initial `sta->dead` test, be delayed, and resume during the teardown window.

Not awarded: no concrete UAF, heap OOB write, controlled reclaim, arbitrary write, disclosure, LPE, or proven C/I impact. B5-R and B3-PENDING do not apply. There is no authorization decision, so B4-PENDING does not apply.

3. Reachability analysis

The assessed actor is an adjacent wireless peer, not a local namespace-capability holder or host administrator. An open or otherwise accessible WLAN permits the grounded below-host-admin path; secured WLANs may require association credentials. No host UID 0, device assignment, special hardware beyond ordinary Wi-Fi, or network-namespace privilege is shown as necessary. The race is timing-sensitive, but station interactions can plausibly be retried.

4. Primitive and severity reading

The primitive is a synchronization/lifetime-boundary failure involving active structured station state, not a proven post-free object use. Work that already passed the dead-state check can later consume and modify station/driver state after removal and queue cleanup. The privileged consumer is the host mac80211/driver path; the trust boundary is an adjacent wireless station influencing host station lifecycle and delivery work. Host crash and state corruption are plausible; UAF, arbitrary memory corruption, and cross-boundary privilege compromise remain unproven.

This specific attacker-influenced active-state corruption chain requires Important-vs-Moderate review under the active-state trust-boundary rule. Therefore ImportantCandidate is YES and automatic downgrade is unsafe.

5. One-sentence report phrase

An adjacent wireless peer can race mac80211 station teardown so delayed power-save work consumes and modifies driver-visible station state after its required retirement point.

6. Manual review advice

MANUAL CHECK REQUIRED

Confirm driver-specific callback behavior, exact post-removal state consumption, and whether any implementation turns the stale delivery into a concrete UAF or stronger corruption primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: wifi: mac80211: drain PS delivery work during station teardown
Commit: 843d3a1e6f25027ac85f88f67b95d82c67306dee
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=843d3a1e6f25027ac85f88f67b95d82c67306dee

Commit description:

Removing an AP or mesh station can notify the driver and wake TXQs after
the station has already been removed from the driver, and can update
num_sta_ps and the power-save queues after station cleanup has purged
them.

sta_deliver_ps_frames() tests sta->dead only before it starts delivery. A
worker that passes that test can be delayed while teardown sets sta->dead
and removes the station from the driver; when it resumes it still runs the
full delivery.

The existing cancel_work_sync() sits near the end of
__cleanup_single_sta(), after the final driver state transition and after
PS accounting and queue purging, so it drains the worker only once the
state it has to protect has already changed. Before commit d34ba21
("mac80211: don't delay station destruction") cleanup was deferred
through the same ordered workqueue as the delivery work, which kept the
two ordered.

Cancel the work after setting sta->dead and before moving the driver
state, and move the existing cancellation to the start of
__cleanup_single_sta(). The first drain closes the driver-lifetime window;
driver callbacks during the remaining state transitions can still queue
drv_deliver_wk through ieee80211_sta_block_awake(), so retain the second
drain at the start of __cleanup_single_sta(). That drain also covers
insertion failures, which reach cleanup without setting sta->dead.

Fixes: d34ba21 ("mac80211: don't delay station destruction")
Cc: stable@vger.kernel.org
Assisted-by: LLM sparse smatch coccinelle kasan
Signed-off-by: Zhao Li <enderaoelyther@gmail.com>
Link: https://patch.msgid.link/20260916113735.31029-1-enderaoelyther@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/mac80211/sta_info.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=843d3a1e6f25027ac85f88f67b95d82c67306dee

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

The original Linux kernel CVE announcement for CVE-2026-98706 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98706

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:L/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:L/I:L/A:H
  The Best / paranoid CVSS score: 6.4

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: 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: YES
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).