[CVE-2026-98575][MODERATE REGULAR] nfc: pn533: fix OOB read in pn533_acr122_is_rx_frame_valid() [ Upstream

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

CVE: CVE-2026-98575
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: nfc: pn533: fix OOB read in pn533_acr122_is_rx_frame_valid() [ Upstream
Commit: 8db3b1e012a8b25078dfa1efabe3d0cd2916dcba
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8db3b1e012a8b25078dfa1efabe3d0cd2916dcba
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98575
Analysis date: Sun, 18 Oct 2026 22:37:08 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A malicious ACR122-compatible USB device can supply an invalid CCID data length that causes an out-of-bounds kernel read in pn533 frame validation and may crash the host, but no write, disclosure path, or privilege-escalation primitive is established.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-98575 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98575

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 REGULAR
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-2026-98575	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98575 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (final Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H';CWE-125;CWE-129;*CWE-20;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.2';DESCR 'An out of bounds read occurs in pn533_acr122_is_rx_frame_valid because the CCID data length supplied by an ACR122 USB response is used as an index into frame data without a complete lower and upper bounds check. A malicious or malfunctioning USB device can provide a value of one to underflow the datalen minus two calculation or provide a large value to read beyond the received frame. The confirmed primitive is an attacker controlled invalid kernel memory read. It can trigger an Oops or kernel panic when the calculated address reaches invalid memory and therefore cause denial of service. For the CVSS the PR:N value is used because no account or local software privilege is required after an attacker controlled USB device is connected. AV:P is used because exploitation depends on physical attachment or equivalent control of the USB peripheral and is not remotely reachable over an ordinary network. The base impact is C:N I:N A:H. The paranoid score uses C:L I:N A:H because device observable validation behavior may provide a limited oracle for whether an out of bounds byte matches the checked value, but the code does not provide a write primitive or a supported privilege escalation path. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 5.2 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 2.9 and ActionableScore 1 with primitive class CLASS_C and manual review RECOMMENDED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	OOB USB SIMPLEFIX HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: -1
* Conservative score: 0
* Raw paranoid score: -1
* Paranoid score: 0
* Applied score bound: -1 -> 0 because ActionableScore has a minimum of zero.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Positive signals:

* +1 Reliable kernel crash or strong DoS. The device controls `ccid.datalen` and can select an index far outside the received USB frame. Reaching unmapped memory or a guarded allocation can produce an Oops, KASAN failure, or kernel panic.
* +0 Limited OOB read. The vulnerable operation only reads a byte and compares it with `0x63`. It does not write through the invalid address.

Negative signals:

* -2 Physical and specialized-device prerequisite. Triggering requires a malicious or malfunctioning ACR122-compatible USB peripheral, or equivalent control of its USB responses. No network or ordinary local-software trigger is established.

Important signals not awarded:

* No confidentiality point. The OOB byte is not copied to userspace, the network, or the USB device. A device-observable oracle is conceivable but not established by the supplied call path.
* No integrity point. The patch establishes no OOB write, UAF, shared-backing modification, or protected-state corruption.
* No extra availability point. The possible Oops or panic is already represented by the single DoS point.
* No authorization-bypass signal. The changed condition validates an input length rather than enforcing credentials, capabilities, or access policy.
* No B5-R signal. The defect is an OOB read, not a retry-accumulated heap OOB write.
* No B3-PENDING signal. There is no write to shared or file-backed storage.
* No V32, V33, or V34 signal. No skb checksum metadata, active structured-state write, privileged downstream consumer, or network trust-boundary chain exists.
* No strong exploitation leverage. Controlled reclaim, arbitrary readback, arbitrary write, callback influence, and privilege escalation are not demonstrated.

3. Reachability analysis

A malicious physical actor can attach an ACR122-compatible USB device that returns an attacker-selected `ccid.datalen`. Once the device is attached and handled by the driver, no host UID 0 account, capability, or host-administrator operation is required for the malformed response itself. Therefore `HostAdminRequired=NO` and `RequiresHostUID0=NO`.

The path is physical rather than remotely network reachable. No namespace or delegated capability participates, so `NamespaceScopedPrivilege=NO`. Use of the vulnerable path requires the PN533 ACR122 USB driver and compatible or emulated hardware. There is no race or retry requirement. The attacker can repeatedly send malformed responses while the device remains connected.

4. Primitive and severity interpretation

The exact primitive is an attacker-indexed kernel OOB read. A value of one underflows the `datalen - 2` expression, while a sufficiently large value indexes beyond the received frame. The read affects a validation branch, but the supplied context does not establish that the byte is disclosed or that accepting or rejecting the frame produces a separate security-sensitive operation.

This is neither a UAF nor an active structured-object lifetime violation. There is no release, refcount mutation, stale reference, or post-lifetime access. The issue is classified as `CLASS_C` because the supported consequence is invalid memory access and possible crash without an independently useful corruption primitive.

The demonstrated consequence is denial of service through an Oops or panic. A limited observation oracle is a theoretical possibility, but no response channel or recoverable byte-disclosure mechanism is shown. Privilege escalation and kernel-memory modification are unsupported.

`ImportantCandidate=NO` because no write, disclosure path, authorization bypass, or unresolved cross-boundary corruption chain is established. `AutoDowngradeAllowed=YES` because this is a physically triggered, constrained read-only defect whose supported impact is crash or DoS. Operational severity is Low-like to Moderate despite the need to fix the memory-safety violation.

5. One-sentence report phrase

A malicious ACR122-compatible USB device can supply an invalid CCID data length that causes an out-of-bounds kernel read in pn533 frame validation and may crash the host, but no write, disclosure path, or privilege-escalation primitive is established.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

The attacker-controlled OOB read should be checked against the complete receive-buffer allocation and error-response path, but current evidence supports a constrained physical DoS rather than an Important-grade primitive.

7. Call-site confidence

Call-site confidence: medium

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UPSTREAM PATCH SUMMARY
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Patch: nfc: pn533: fix OOB read in pn533_acr122_is_rx_frame_valid() [ Upstream
Commit: 8db3b1e012a8b25078dfa1efabe3d0cd2916dcba
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8db3b1e012a8b25078dfa1efabe3d0cd2916dcba

Changed files:
  drivers/nfc/pn533/usb.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=8db3b1e012a8b25078dfa1efabe3d0cd2916dcba

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

The original Linux kernel CVE announcement for CVE-2026-98575 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98575

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:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 5.2

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: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).