* [CVE-2026-93274][LOW] pinctrl: bcm2835: Don't remove an unregistered GPIO chip [ Upstream
@ 2026-09-24 19:06 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-24 19:06 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-93274
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: pinctrl: bcm2835: Don't remove an unregistered GPIO chip [ Upstream
Commit: d428863ca8baa4e9eaf781266ac219b017dcf277
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d428863ca8baa4e9eaf781266ac219b017dcf277
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93274
Analysis date: Thu, 24 Sep 2026 15:06:25 -0400
ActionableScore: 1
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-2026-93274 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93274
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-2026-93274 LOW https://www.kernelcve.org/list/?q=CVE-2026-93274 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-703;CWE-754;BEST CVSS score: '4.1';DESCR 'A NULL pointer dereference can occur in the BCM2835 pinctrl driver when devm_pinctrl_register fails and the error path calls gpiochip_remove for a GPIO chip that has not yet been registered. The unregistered gpio chip has a NULL gpiodev pointer and gpiochip_remove can therefore cause a kernel panic. For the CVSS the PR:H is used because reliably reaching this path normally requires administrative control over driver loading platform configuration or device initialization. The issue is not network reachable and requires a specific registration failure during the local driver probe path. Impact is denial of service through a kernel panic. No confidentiality or integrity impact is supported because the patch indicates a NULL pointer dereference in an error cleanup path rather than a memory corruption primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) YES DANGER NULLPTR DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH YES NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Reliable kernel crash or strong DoS. The patch and commit directly identify a NULL pointer dereference in gpiochip_remove that can panic the kernel when devm_pinctrl_register fails.
* No UAF or lifetime-corruption signal. gpiochip_remove is called on an unregistered object, but no object was freed and later reused.
* No controlled write, arbitrary write, controlled reclaim, disclosure, integrity impact, authorization bypass, or privilege escalation primitive is established.
* No remote reachability signal. This is a local BCM2835 platform-driver probe error path.
* No privilege penalty was applied. The supplied patch does not establish the complete privilege boundary for inducing the registration failure. HostAdminRequired is therefore UNKNOWN rather than YES.
* No hardware rarity penalty was applied. BCM2835 is platform-specific, but the supplied evidence does not establish a physical-only attacker requirement or unusual hardware access prerequisite.
* No additional availability point was added because the kernel panic is the same demonstrated DoS consequence.
3. Reachability analysis
The vulnerable operation occurs during bcm2835_pinctrl_probe when devm_pinctrl_register fails before gpiochip_add_data has registered the GPIO chip. The supplied evidence does not show that an ordinary local user can cause this driver-probe failure, nor does it prove that host-admin-equivalent privileges are always required to reach it.
The path is not network reachable. No namespace-scoped capability path is identified. There is no evidence that a container, user namespace, network namespace, or delegated capability can perform the complete trigger sequence. The affected driver targets BCM2835 platform hardware and is normally initialized as part of platform-device probing, but this does not itself establish an attacker-controlled trigger.
4. Primitive and severity interpretation
The exact primitive is an invalid NULL pointer dereference in an error-cleanup path. After devm_pinctrl_register fails, bcm2835_pinctrl_probe calls gpiochip_remove even though gpiochip_add_data has not run and gpio_chip.gpiodev remains NULL.
This is not an active structured-object UAF, fixed stale storage case, double release, refcount mutation, use-after-free, or ownership violation. The demonstrated consequence is a kernel crash or panic. A stronger consequence such as memory corruption, information disclosure, integrity compromise, or local privilege escalation is speculative and unsupported by the patch.
The issue is CLASS_C because it is a crash-capable invalid-state error path without an independently useful corruption primitive. ImportantCandidate is NO because no unresolved exploitation leverage beyond the NULL dereference is established. AutoDowngradeAllowed is YES because this is a constrained crash-only issue with no demonstrated lifetime, reuse, write, authorization, or security-boundary primitive.
5. One-sentence report phrase
A NULL pointer dereference in the BCM2835 pinctrl driver can cause a kernel panic if pinctrl registration fails before the GPIO chip is registered and the error path calls gpiochip_remove.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
The patch establishes a constrained NULL dereference in a platform-driver initialization error path, with kernel crash as the only supported consequence and no demonstrated memory-corruption or privilege-escalation primitive.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: pinctrl: bcm2835: Don't remove an unregistered GPIO chip [ Upstream
Commit: d428863ca8baa4e9eaf781266ac219b017dcf277
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d428863ca8baa4e9eaf781266ac219b017dcf277
Changed files:
drivers/pinctrl/bcm/pinctrl-bcm2835.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=d428863ca8baa4e9eaf781266ac219b017dcf277
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93274 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93274
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: Not available
The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 4.1
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: unknown
Paranoid ActionableScore: 1
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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