[CVE-2026-68126][MODERATE 7.0] mac802154: hold an interface reference across the scan worker

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

CVE: CVE-2026-68126
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: mac802154: hold an interface reference across the scan worker
Commit: bd7110f0caa32426140ff302a209c53294ef2cfd
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bd7110f0caa32426140ff302a209c53294ef2cfd
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68126
Analysis date: Mon, 10 Aug 2026 17:39:09 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A race in mac802154 scan worker can leave a stale `net_device` pointer after concurrent interface removal, causing a local CAP_NET_ADMIN-triggered slab-use-after-free and likely kernel crash, with limited but review-worthy LPE concern in delegated network-admin environments.

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

The original Linux kernel CVE announcement for CVE-2026-68126 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68126

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-2026-68126	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;*CWE-664;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'mac802154_scan_worker can keep using sdata dev after leaving the RCU read side and outside rtnl protection. A concurrent DEL_INTERFACE or PHY teardown can unregister and asynchronously free the netdev through netdev_run_todo while the scan worker still dereferences the stale pointer, producing a race based use-after-free. For the CVSS the PR:L is used for the paranoid score because CAP_NET_ADMIN may be delegated to container root or service accounts and should not always be treated as full host administrator control in practical risk analysis. The issue is not network reachable by ordinary packet traffic and is triggered through local control plane operations such as TRIGGER_SCAN racing DEL_INTERFACE. Impact is at least local denial of service via kernel crash. In the worst still defensible case, the UAF may allow confidentiality or integrity impact and possible privilege escalation, so manual review is required.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 4)  SKIP CVE-2026-68126 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 57588c71177f0bfc08509c2c3a9bfe32850c0786 YES  NO NO unknown 	MAYBE	LOCK INIT UAF LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Memory corruption, weak primitive: +1. This is a race-dependent KASAN slab-use-after-free, but the patch does not show controlled reclaim, overwrite, callback control, or type confusion.
* Real lifetime corruption: +1. The bug is a netdev lifetime bug where `sdata->dev` can be freed while the worker still uses it.
* Reliable kernel crash / strong DoS: +1. The commit explicitly describes KASAN slab-use-after-free failure traces.
* Hard or unreliable race / special timing required: -1. Triggering requires racing `TRIGGER_SCAN` against `DEL_INTERFACE` or PHY removal.
* Requires CAP_NET_ADMIN in typical deployments: -2. Both relevant operations are described as requiring CAP_NET_ADMIN.
* Availability impact realistic: +1. A kernel UAF in this path can realistically crash the system.

Paranoid additions / changed interpretation:

* Reduced privilege CAP_NET_ADMIN interpretation: +1 relative to conservative. CAP_NET_ADMIN may be delegated to container root, service accounts, or limited network-management contexts, so this is not always equivalent to full host root in practical triage.
* Weak LPE concern: +1. The UAF affects a freed `net_device` pointer in a network subsystem worker and can flow through beacon transmit / cleanup paths. There is no demonstrated exploit primitive, but the lifetime class is serious enough for manual review.

No remote/network packet reachability is counted. No strong LPE, arbitrary write, callback hijack, or attacker-controlled reclaim is demonstrated.

## 3. Reachability analysis

The bug is triggered locally through the mac802154 / nl802154 control plane by racing scan start with interface deletion or PHY teardown. The commit states that both `TRIGGER_SCAN` and `DEL_INTERFACE` require CAP_NET_ADMIN.

In normal host deployments this is a privileged local bug. In containerized or delegated network-management environments, CAP_NET_ADMIN may be available to less trusted actors, so the paranoid score treats the privilege barrier as weaker than full host-root control.

The path is not reachable by ordinary network packets. It requires IEEE 802.15.4 / mac802154 support and relevant interface or PHY state, so exposure is narrower than core TCP/IP or netfilter packet paths.

## 4. Severity interpretation

This is stronger than an ordinary Moderate because it is a real race-based UAF with KASAN evidence in a kernel networking subsystem. Realistic demonstrated impact is local DoS through kernel crash.

Theoretical privilege escalation is possible only in a paranoid sense. The patch does not show controlled object replacement, write-after-free, callback dispatch, or a reliable reclaim primitive. Therefore this should not be treated as proven Important/LPE, but it should not be auto-closed without review.

## 5. One-sentence report phrase

A race in mac802154 scan worker can leave a stale `net_device` pointer after concurrent interface removal, causing a local CAP_NET_ADMIN-triggered slab-use-after-free and likely kernel crash, with limited but review-worthy LPE concern in delegated network-admin environments.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a confirmed race-based UAF in a networking subsystem, and CAP_NET_ADMIN may be delegated in containers or service contexts. The main proven impact is DoS, but the lifetime primitive warrants manual review before downgrading or auto-closing.

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

Patch: mac802154: hold an interface reference across the scan worker
Commit: bd7110f0caa32426140ff302a209c53294ef2cfd
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bd7110f0caa32426140ff302a209c53294ef2cfd

Commit description:

mac802154_scan_worker() captures the scanning sub-interface under RCU
and then keeps dereferencing sdata->dev after rcu_read_unlock() and
outside the rtnl -- in the failure traces, in
mac802154_transmit_beacon_req() (skb->dev = sdata->dev), and in the
end_scan cleanup. Nothing keeps that netdev alive across the worker
iteration.

A concurrent DEL_INTERFACE or PHY removal can unregister the interface
once the worker drops the rtnl between its two drv_set_channel()
sections. unregister_netdevice() frees the netdev asynchronously from
netdev_run_todo() with the rtnl already dropped, so neither holding the
rtnl nor the per-PHY IEEE802154_IS_SCANNING flag prevents a stale worker
iteration from dereferencing the freed netdev -- a KASAN
slab-use-after-free, reachable by racing TRIGGER_SCAN against
DEL_INTERFACE (both CAP_NET_ADMIN).

Pin the netdev with netdev_hold() while the RCU read lock is still held,
and release it at every worker exit.

Fixes: 57588c7 ("mac802154: Handle passive scanning")
Cc: stable@vger.kernel.org
Signed-off-by: Ibrahim Hashimov <security@auditcode.ai>
Link: https://patch.msgid.link/20260721211228.34578-1-security@auditcode.ai
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/mac802154/scan.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=bd7110f0caa32426140ff302a209c53294ef2cfd

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

The original Linux kernel CVE announcement for CVE-2026-68126 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68126

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:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

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: 3
  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: NO
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).