[CVE-2026-93281][MODERATE REGULAR] wifi: rtw89: fix HE extended capability length check [ Upstream

[CVE-2026-93281][MODERATE REGULAR] wifi: rtw89: fix HE extended capability length check [ Upstream

[AL-KERNEL]

CVE: CVE-2026-93281
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: rtw89: fix HE extended capability length check [ Upstream
Commit: eddf53f1edb0cf7f302bd15cdb47cca90948c205
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eddf53f1edb0cf7f302bd15cdb47cca90948c205
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93281
Analysis date: Thu, 24 Sep 2026 14:43:07 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-93281 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93281

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: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-93281	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-93281 CHECK WITH IMPACT FROM ORIG NN IMPORTANT	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:L/A:L';CWE-125;CWE-193;*CWE-20;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '6.3';DESCR 'An off by one length check in the rtw89 HE extended capability parser allows data byte 10 to be read when the received information element contains only 10 data bytes. A nearby wireless attacker can send a malformed 802.11 management frame with a truncated extended capability element and trigger an out of bounds read in the kernel Wi Fi driver. For the CVSS the PR:N because no account or local code execution on the target is required. The attack vector is AV:A because the attacker must be within Wi Fi radio range of a vulnerable rtw89 device. The expected impact is at least incorrect capability handling and potentially a local driver or kernel denial of service if the read reaches an invalid allocation boundary. No controlled write UAF or demonstrated privilege escalation primitive is shown. YES REQUIRES MANUAL CHECK';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	REMOTE SIMPLEFIX NETWORK LINUS  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	NO	NO	checked

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

ActionableScore=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: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +2 Directly network-triggerable adjacent wireless input. A nearby attacker can transmit malformed 802.11 management information elements that may reach the rtw89 parser on a vulnerable Wi Fi device.
* +0 Limited out of bounds read. The patch establishes a one byte read beyond the declared Extended Capabilities IE payload length. This is not an out of bounds write, UAF, refcount mutation, or active object lifetime violation.
* +0 Reliable kernel crash not established. The patch fixes a bounds check but does not report an Oops, panic, KASAN finding, or reproducible denial of service.
* +0 Confidentiality not awarded. No kernel bytes are copied to userspace, network output, logs, or another attacker observable interface.
* +0 Integrity not awarded. The vulnerable operation only reads data and affects capability interpretation. No attacker controlled write or protected state modification is demonstrated.
* +0 Strong exploitation leverage not awarded. Controlled reclaim, arbitrary write, type confusion, callback influence, privilege escalation, and security boundary bypass are not established.
* +0 No hardware penalty. The rtw89 driver is adapter specific, but affected Realtek Wi Fi hardware is not evidence of rare physical only access or a materially restricted attacker model.

3. Reachability analysis

A nearby wireless attacker is the relevant attacker model. The attacker does not need an account, local code execution, administrative privileges, or a network namespace on the victim. They need radio range to a system using an affected rtw89 Wi Fi adapter and must cause the driver to process a malformed HE Extended Capabilities information element.

The exact visible call chain is not included, but the use of cfg80211_find_elem on received information elements strongly indicates processing of wireless BSS or management frame information elements. The affected device must be active on a relevant channel or otherwise process attacker supplied management information. This is an adjacent wireless attack surface, not Internet remote reachability.

No host administrative privilege is required on the victim for the external wireless attacker. Namespace scoped privilege is not relevant because the trigger is delivered over the Wi Fi radio interface and does not require a privileged local namespace operation. No special host configuration is established beyond use of the vulnerable rtw89 driver and HE capability processing.

4. Primitive and severity interpretation

The exact defect is an off by one validation error. The code accepted an Extended Capabilities IE with datalen equal to 10 and then accessed data[10], which requires at least 11 bytes. If the malformed element is followed by another IE, the read may consume a byte outside the declared element payload but still within the larger received IE buffer. If the malformed element ends at the allocation boundary, it may read one byte beyond that buffer.

This is a bounded one byte invalid read. It is not a UAF, use after free, double free, stale reference, OOB write, refcount mutation, or ownership violation. The immediate practical result may be incorrect interpretation of the OBSS narrow bandwidth RU tolerance capability. A crash is possible only as an unproven boundary case and is not demonstrated by the supplied patch.

PrimitiveClass is CLASS_C because the established behavior is invalid input handling with at most a limited invalid read and potential DoS behavior. There is no meaningful exploitation primitive beyond that invalid read. ImportantCandidate is NO because no attacker useful disclosure, write, controlled corruption, or privilege boundary bypass is established. AutoDowngradeAllowed is YES because the patch does not establish unresolved kernel lifetime corruption or a security boundary primitive.

The supplied paranoid CVSS suggestion with C:L I:L A:L is not supported by the patch alone. There is no demonstrated disclosure path for confidentiality impact, no write or protected state modification for integrity impact, and no demonstrated crash for high availability impact.

5. One-sentence report phrase

A nearby Wi Fi attacker may send a malformed HE Extended Capabilities information element with a truncated payload and trigger a one byte out of bounds read in the rtw89 driver, but no information disclosure, memory write, privilege escalation, or reliable kernel crash is established.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

The input is externally attacker controlled over the adjacent wireless attack surface and reaches kernel driver parsing code, but the patch supports only a limited OOB read without a demonstrated disclosure, crash, or corruption primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: wifi: rtw89: fix HE extended capability length check [ Upstream
Commit: eddf53f1edb0cf7f302bd15cdb47cca90948c205
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eddf53f1edb0cf7f302bd15cdb47cca90948c205

Changed files:
  drivers/net/wireless/realtek/rtw89/mac.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=eddf53f1edb0cf7f302bd15cdb47cca90948c205

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

The original Linux kernel CVE announcement for CVE-2026-93281 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93281

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:L/PR:N/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
  The Best / paranoid CVSS score: 6.3

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: unknown
  Paranoid ActionableScore: 2

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).