[CVE-2026-93213][LOW] of: fix out-of-bounds read in of_alias_scan() stem parser

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

CVE: CVE-2026-93213
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: of: fix out-of-bounds read in of_alias_scan() stem parser
Commit: fd0c7bbda81c0e0c1cb7b68d267b87371584f560
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fd0c7bbda81c0e0c1cb7b68d267b87371584f560
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93213
Analysis date: Thu, 24 Sep 2026 14:12:11 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-93213 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93213

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-93213	LOW	https://www.kernelcve.org/list/?q=CVE-2026-93213 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:N';CWE-125;CWE-193;BEST CVSS score: '0';DESCR 'An out of bounds read in of_alias_scan occurs because the stem parser evaluates end minus one before verifying that end is greater than start. A malformed Device Tree alias property with an empty or all digit name can cause a one byte read before the property name. For the CVSS the PR:H is used because reliable triggering normally requires control of the boot Device Tree or privileged Device Tree overlay management. The issue is not network reachable. The patch context does not show a disclosure sink, memory write, use after free, or reliable crash condition. Impact is therefore assessed as no demonstrated confidentiality integrity or availability impact.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	YES	OOB SIMPLEFIX IMPROVEONLY LINUS TEST  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS	NO	NO	checked

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

ActionableScore=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +0 Limited invalid read: the loop can read exactly one byte at `end - 1` before validating `end > start`. The read is bounded and only feeds `isdigit`.
* +0 Weak corruption concern: there is no demonstrated write, stale object use, refcount mutation, control-flow effect, or attacker-controlled target.
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Information disclosure not demonstrated. The byte is not copied to userspace, network output, or another observable channel.
* Reliable crash not demonstrated. The preceding byte will commonly remain within the mapped Device Tree blob or adjacent mapped memory.
* Remote reachability not established.
* No negative privilege penalty was applied because host-admin-equivalent control is not positively established from the supplied patch alone.

3. Reachability analysis

The affected code runs while scanning Device Tree aliases. Triggering requires a malformed alias property name that is empty or consists entirely of digits.

The normal source of the initial Device Tree is boot firmware or a bootloader. A runtime Device Tree overlay may also reach related parsing paths, but the supplied patch does not establish that an ordinary unprivileged user can load such an overlay or drive the complete vulnerable path.

Host-admin-equivalent privilege is therefore UNKNOWN rather than YES. Below-host-admin reachability is also not established, so HostAdminRequired is not set to NO. There is no evidence that the complete operation is namespace-scoped.

No network input, special hardware, race condition, or repeated lifetime manipulation is involved.

4. Primitive and severity interpretation

The exact primitive is a one-byte out-of-bounds read caused by evaluating `isdigit(*(end - 1))` before checking `end > start`. This is not a UAF, ownership violation, active-object lifetime error, or write primitive.

The stale read is not shown to expose data, alter privileged state, corrupt memory, cause a fault, or influence a security-relevant decision. The consumed value is only used to determine whether the preceding byte is a decimal digit while deriving an alias stem.

PrimitiveClass is NONE because the patch establishes a correctness and bounds-validation defect, but not a meaningful corruption, authorization, ownership, or lifetime primitive. ImportantCandidate is NO and automatic downgrade is allowed because no unresolved exploitation leverage beyond the bounded invalid read is visible.

5. One-sentence report phrase

A one-byte out-of-bounds read in the Device Tree alias stem parser occurs when an empty or all-digit alias name is processed, but no disclosure, memory corruption, or reliable denial of service consequence is demonstrated.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch fixes a bounded read-only parser defect with no demonstrated disclosure, write, crash, privilege-boundary bypass, or lifetime-corruption primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: of: fix out-of-bounds read in of_alias_scan() stem parser
Commit: fd0c7bbda81c0e0c1cb7b68d267b87371584f560
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fd0c7bbda81c0e0c1cb7b68d267b87371584f560

Commit description:

The stem parser tests isdigit(*(end - 1)) before checking end > start
and so reads one byte before the property name when the name is empty
or all digits. Check the bound first.

Fixes: 611cad7 ("dt: add of_alias_scan and of_alias_get_id")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-fable-5 [Claude Code]
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260805-nh-of-alias-overlay-v6-1-74f21d440819@nexthop.ai
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/of/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=fd0c7bbda81c0e0c1cb7b68d267b87371584f560

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

The original Linux kernel CVE announcement for CVE-2026-93213 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93213

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:N
  The Best / paranoid CVSS score: 0

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: 0

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).