[CVE-2026-93806][MODERATE REGULAR] wifi: cfg80211: validate assoc response length before status and IE access [ Upstream

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

CVE: CVE-2026-93806
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: cfg80211: validate assoc response length before status and IE access [ Upstream
Commit: a57310600c1e2b9ada0f37c96e8f48aef47d3093
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a57310600c1e2b9ada0f37c96e8f48aef47d3093
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93806
Analysis date: Thu, 24 Sep 2026 19:29:10 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-93806 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93806

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
======================================================================

CVE-2026-93806	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-93806 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H';CWE-125;*CWE-20;CWE-191;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.1';DESCR 'A short or malformed WiFi Association Response can reach cfg80211_rx_assoc_resp before the received frame length is validated. The function can read the association status outside the received frame and can calculate an underflowed response IE length, which may cause an out-of-bounds read and potentially a kernel crash or other denial of service. For the CVSS the PR:N value is used because an attacker only needs adjacent WiFi network access and does not require local code execution or an account on the target. The attack vector is AV:A because the attacker must be within wireless range or control a reachable access point. The base assessment uses AC:H because the malicious frame must be delivered during the association response processing state. The paranoid assessment uses AC:L for a rogue or spoofed access point scenario where the target automatically associates or roams. Impact is at least denial of service. Limited confidentiality impact is retained only for the paranoid score because the invalid IE pointer and length can potentially expose out-of-bounds data to local wireless event consumers. No concrete write primitive or privilege escalation path is demonstrated. WiFi attacks normally require radio proximity and are not directly reachable from the public Internet.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3)	YES	REMOTE  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	NO	NO	checked

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

ActionableScore=3
ActionableScoreLower=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 3
* Paranoid score: 3
* Final recommended bucket: **Borderline / manual review recommended**::

No floor or cap was applied.

2. Signal breakdown

* +2 Direct attacker controlled wireless frame reachability. An adjacent attacker or a malicious reachable access point can send an Association Response into the cfg80211 association handling path without local execution or a local account on the victim.
* +1 Paranoid only. The malformed frame can produce an underflowed response IE length which is carried in cfg80211_connect_resp_params to later connection-result processing. This gives a technically defensible potential kernel out of bounds read and crash path beyond the initial status-field access.

Important non-awarded signals:

* +0 Real UAF. No freed object or stale post-lifetime reference is involved.
* +0 Controlled reclaim or object replacement. Not demonstrated.
* +0 Arbitrary or directed kernel write. Not demonstrated.
* +0 Confidentiality. The patch establishes an invalid read, but no attacker-readable disclosure path is established. Local nl80211 event handling alone does not demonstrate that the wireless attacker receives leaked bytes.
* +0 Integrity. No write primitive or security-state modification is established.
* +0 Privilege escalation. No LPE or authorization-boundary bypass is demonstrated.
* +0 Reliable kernel crash in the conservative score. The patch prevents invalid accesses and an underflowed length, but the supplied context does not demonstrate a deterministic panic on all affected configurations.
* -0 Timing penalty. Association-state timing is required, but the evidence does not establish a narrow or uncontrollable race.
* -0 configuration or hardware penalty. WiFi is common hardware and malformed management-frame handling is not a niche subsystem condition.

3. Reachability analysis

An attacker needs adjacent WiFi reachability, for example by operating a malicious access point, impersonating a reachable BSSID, or transmitting an Association Response during the victim station association process. The attacker does not need a local user account, local code execution, host root, CAP_NET_ADMIN, or namespace capabilities on the victim.

The vulnerable operation is entered from received wireless management-frame processing. This is network-adjacent exposure, AV:A, rather than public-Internet AV:N exposure. A successful trigger depends on the station being in the association-response processing state and accepting or processing the relevant frame context.

No namespace-scoped privilege is relevant to the attacker path. No special boot setting, privileged host setup, or rare physical device requirement is established beyond the victim having an affected active WiFi interface.

4. Primitive and severity interpretation

The concrete primitive is an attacker-controlled short Association Response causing cfg80211_rx_assoc_resp to read the association status before validating the received frame length. The original code also calculated resp_ie_len by subtracting the normal Association Response IE offset from data->len before checking that data->len was large enough. A short frame can therefore cause unsigned length underflow and leave a response IE pointer and very large length inconsistent with the actual frame buffer.

This is an invalid input and out of bounds read class issue, not a UAF, double free, active-object lifetime violation, arbitrary write, or controlled type confusion. The affected data is a received management frame, not fixed stale storage or a reclaimed active object.

The demonstrated consequence is malformed wireless-frame processing with a plausible kernel fault or denial of service. The paranoid score preserves a limited additional concern because the underflowed response IE length is stored in connection-result parameters and can reach subsequent processing. However, no controlled disclosure, write, privilege escalation, or attacker-controlled post-corruption state is established.

PrimitiveClass is CLASS_C because the evidence supports invalid-state and out of bounds read behavior with potential crash impact, but no independently useful memory-corruption primitive. ImportantCandidate is NO because the supplied patch does not establish meaningful exploitation leverage beyond denial of service. AutoDowngradeAllowed is YES because there is no unresolved UAF, repeated lifetime mutation, authorization bypass, controlled corruption, or ownership violation.

5. One-sentence report phrase

A malformed short WiFi Association Response can cause cfg80211 to access fields before validating frame length and to derive an underflowed response IE length, creating a network-adjacent denial of service risk without a demonstrated disclosure, write, or privilege-escalation primitive.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

The issue is directly reachable through attacker-controlled adjacent wireless traffic and includes both an out of bounds status read and an underflowed length propagated into later connection-result processing. Review affected driver and mac80211 delivery paths to determine whether malformed Association Responses can reliably reach this function and whether downstream consumers can produce a deterministic crash.

7. Call-site confidence

Call-site confidence: medium

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

Patch: wifi: cfg80211: validate assoc response length before status and IE access [ Upstream
Commit: a57310600c1e2b9ada0f37c96e8f48aef47d3093
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a57310600c1e2b9ada0f37c96e8f48aef47d3093

Changed files:
  net/wireless/mlme.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=a57310600c1e2b9ada0f37c96e8f48aef47d3093

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

The original Linux kernel CVE announcement for CVE-2026-93806 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93806

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:H
  The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 7.1

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).