[CVE-2026-72165][LOW] mtd: rawnand: fix condition in 'nand_select_target()'

[CVE-2026-72165][LOW] mtd: rawnand: fix condition in 'nand_select_target()'

[AL-KERNEL]

CVE: CVE-2026-72165
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: mtd: rawnand: fix condition in 'nand_select_target()'
Commit: 483a8a8581ee1274ec70e2561492096d4a7305e6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=483a8a8581ee1274ec70e2561492096d4a7305e6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72165
Analysis date: Sat, 15 Aug 2026 07:14:23 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-72165 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72165

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: YES

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

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

CVE-2026-72165	LOW	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:L/I:L/A:H';CWE-193;CWE-129;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.8';DESCR 'raw NAND target selection used an off by one bounds check in nand_select_target, allowing cs equal to nanddev_ntargets to pass the warning check and become chip cur_cs. This could leave the driver in an invalid chip select state and may lead to wrong target access or a driver specific crash if a caller reaches this invalid value. For the CVSS the PR:L value is used for the paranoid case because some systems expose MTD access to local service accounts or reduced capability administrative users, although reliable triggering still depends on a buggy NAND path or device specific operation. The issue is not network reachable. Impact is mainly denial of service or incorrect NAND access. A limited integrity impact is kept only for the paranoid score because an invalid target could affect device specific data operations.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	SIMPLEFIX LINUS  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	YES	NO	checked

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

ActionableScore=2
ActionableScoreLower=0

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

2. Signal breakdown
* Weak/indirect corruption candidate: +1 paranoid only. The invalid `cs == nanddev_ntargets()` value can be stored in `chip->cur_cs`, but the patch does not show UAF, OOB write, type confusion, attacker-controlled overwrite, or callback control.
* Important storage/device path: +1 paranoid only. Raw NAND target selection can affect persistent flash operations, but only in device-specific paths.
* Integrity impact plausible: +1 paranoid only. A wrong NAND target could theoretically affect the wrong chip target or data operation, but this is not demonstrated as a cross-permission or arbitrary write primitive.
* Availability impact plausible: +1 paranoid only. Invalid target selection may cause WARN, failed device operation, or driver-specific malfunction.
* Hard or unreliable trigger: -1. The bad value must reach an internal NAND helper through a buggy caller or device-specific path.
* Rare hardware/device-specific exposure: -1. Raw NAND multi-target configurations are not broad default exposure.
* Requires privileged or special device access in typical deployments: conservative -2. Ordinary users normally cannot drive raw MTD/NAND management paths directly.

3. Reachability analysis
The affected function is an internal raw NAND helper, not a direct syscall or network parser. Triggering requires a caller to pass an invalid chip-select value equal to the target count. In typical deployments this is reachable only through privileged kernel/device-management or MTD operations, not by a remote attacker. Namespaces do not materially improve reachability unless a container or service is explicitly delegated raw MTD device access. Call-site confidence: low to medium, because the provided patch does not include callers.

4. Severity interpretation
This behaves like a low-end correctness and validation bug with possible device-specific DoS or wrong-target NAND access. Theoretical integrity impact exists only in the paranoid interpretation. Realistic exploitation evidence for memory corruption, privilege escalation, or cross-boundary data modification is not present.

5. One-sentence report phrase
An off-by-one bounds check in `nand_select_target()` could allow an invalid NAND target index to be recorded, potentially causing device-specific wrong-target access or DoS, but no concrete memory corruption or privilege-escalation primitive is shown.

6. Manual review recommendation
NO MANUAL CHECK NEEDED - NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED.
Reason: no remote reachability, no concrete memory corruption primitive, no demonstrated LPE path, and triggering depends on privileged or device-specific raw NAND paths.

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

Patch: mtd: rawnand: fix condition in 'nand_select_target()'
Commit: 483a8a8581ee1274ec70e2561492096d4a7305e6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=483a8a8581ee1274ec70e2561492096d4a7305e6

Commit description:

'cs' here must be in range [0:nanddev_ntargets[.

Cc: stable@vger.kernel.org
Fixes: 32813e2 ("mtd: rawnand: Get rid of chip->numchips")
Signed-off-by: Arseniy Krasnov <avkrasnov@rulkc.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/mtd/nand/raw/nand_base.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=483a8a8581ee1274ec70e2561492096d4a7305e6

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

The original Linux kernel CVE announcement for CVE-2026-72165 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72165

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:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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).