[CVE-2026-68407][LOW] wifi: nl80211: free RNR data on MBSSID mismatch [ Upstream

[CVE-2026-68407][LOW] wifi: nl80211: free RNR data on MBSSID mismatch [ Upstream

[AL-KERNEL]

CVE: CVE-2026-68407
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: wifi: nl80211: free RNR data on MBSSID mismatch [ Upstream
Commit: fa9592ef7de11f8c7042315d9bc20e91a97f679e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fa9592ef7de11f8c7042315d9bc20e91a97f679e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68407
Analysis date: Mon, 10 Aug 2026 19:44:28 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like auto-close candidate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-68407 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68407

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: LOW
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-2026-68407	LOW	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'nl80211_parse_beacon() can leak an allocated RNR data object when EMA RNR data is rejected because the RNR entry count is smaller than the MBSSID entry count. The rejected object is not yet attached to the beacon data, so returning EINVAL without freeing it causes a memory leak on the error path. This is a local control plane issue through nl80211 AP or beacon configuration rather than a bug triggered by received WiFi traffic. For the CVSS the PR:L is used for the paranoid score because an untrusted local process with delegated CAP_NET_ADMIN or AP management control could repeatedly submit invalid beacon configuration. Impact is denial of service through possible memory exhaustion only. There is no evidence of use after free, out of bounds access, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like auto-close candidate (with actual score 1)	YES	REMOTE SIMPLEFIX  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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

ActionableScore=2
ActionableScoreLower=0

1. ActionableScore
* Conservative score: 0
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like auto-close candidate**

2. Signal breakdown
* Availability impact realistic: +1 in the paranoid interpretation only. Repeated invalid nl80211 beacon configuration could leak memory and eventually contribute to memory pressure or resource exhaustion.
* Broad/common subsystem exposure: +1 in the paranoid interpretation only. nl80211/cfg80211 is a common wireless control-plane subsystem, but the affected path is narrower because it requires AP beacon/EMA MBSSID/RNR configuration.
* Requires admin/root/CAP_NET_ADMIN in typical deployments: -2 for the conservative score. nl80211 AP/beacon configuration is normally restricted to CAP_NET_ADMIN or a privileged WiFi management service.
* No memory corruption signal: +0. The patch only adds kfree(rnr) on an error path before returning EINVAL. There is no UAF, double free, OOB access, stale pointer reuse, arbitrary write, or type confusion.
* No LPE signal: +0. The leaked object is not attached to bcn->rnr_ies and the patch does not show a corruption or object replacement primitive.
* No direct network trigger: +0. This is not triggered by received WiFi frames. It is triggered through local nl80211 control-plane configuration.

3. Reachability analysis
The bug can be triggered by a local process that can submit AP beacon configuration through nl80211 with inconsistent EMA RNR and MBSSID data. In normal deployments this requires CAP_NET_ADMIN or a privileged WiFi/AP management component. A container or namespace setup with delegated CAP_NET_ADMIN could lower the practical privilege boundary, but this is still not a generic unprivileged local trigger. The affected path is not packet-processing and is not remotely reachable over WiFi by merely sending frames. Realistic exploitation requires repeated configuration attempts to accumulate leaked allocations.

4. Severity interpretation
This behaves like a low-end resource leak / ordinary Moderate issue, not an Important-class vulnerability. The theoretical impact is memory exhaustion after repeated abuse, but the patch shows only an error-path leak and no memory corruption, confidentiality impact, integrity impact, or privilege escalation path. The paranoid score remains low because even with delegated CAP_NET_ADMIN the primitive is limited to resource exhaustion.

5. One-sentence report phrase
nl80211_parse_beacon() can leak an allocated RNR object when invalid EMA RNR data is rejected on an MBSSID mismatch, allowing a privileged or delegated CAP_NET_ADMIN local actor to cause limited memory exhaustion through repeated invalid AP beacon configuration.

6. Manual review recommendation
NO MANUAL CHECK NEEDED. This is a straightforward memory leak fix on a local privileged nl80211 configuration error path, with no concrete memory corruption or security-boundary bypass primitive.

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

Patch: wifi: nl80211: free RNR data on MBSSID mismatch [ Upstream
Commit: fa9592ef7de11f8c7042315d9bc20e91a97f679e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fa9592ef7de11f8c7042315d9bc20e91a97f679e

Changed files:
  net/wireless/nl80211.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=fa9592ef7de11f8c7042315d9bc20e91a97f679e

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

The original Linux kernel CVE announcement for CVE-2026-68407 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68407

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:L/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: 0
  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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).