* [CVE-2026-98481][MODERATE REGULAR] nfc: port100: reject frames whose declared length exceeds the received data
@ 2026-10-24 15:08 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-24 15:08 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98481
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: nfc: port100: reject frames whose declared length exceeds the received data
Commit: 0d482995f0cdd0302450aa300c684c642d8ab31f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0d482995f0cdd0302450aa300c684c642d8ab31f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98481
Analysis date: Sat, 24 Oct 2026 11:08:02 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
A malicious Sony Port100 USB device can overstate a response length and make the NFC driver read beyond the received URB buffer, potentially crashing the host.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98481 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98481
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-98481 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98481 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 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-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 'A device controlled datalen value in a Sony Port100 USB response can make port100_data_checksum read beyond the URB transfer buffer because the declared frame size was not compared with urb actual_length. The concrete primitive is an out of bounds kernel read that can cross an allocation boundary and may cause a kernel fault or crash. For the CVSS the PR:N value is used because a malicious physical USB device does not need an authenticated host account after it is connected. The issue is not established as remotely reachable through NFC radio traffic. No out of bounds write or UAF is present. Limited confidentiality impact is retained only for the paranoid score because checksum acceptance may expose a weak behavior oracle for adjacent memory. Automated impact decision path. The original SimpleNet classifier selected IMPORTANT. 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 CVSS and initial triage stage IMPORTANT to MODERATE_KPANIC because the CVSS score, vector or bug class threshold rule was applied. 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 LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS and DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 2.4 and ActionableScore 2 with primitive class CLASS_C and manual review REQUIRED. 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 WRITE OOB SIMPLEFIX HARDWARE LINUS LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
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 base score: 0.
* Conservative score: 0.
* Raw paranoid score: 0.
* Paranoid score: 0.
* No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 firmware/device-mediated external influence: a malicious Port100 USB device controls the 16-bit `datalen`.
* +1 reliable kernel crash concern: checksum processing reads beyond the received URB data and may cross the allocation boundary.
* -2 physical-only/rare-hardware exposure: triggering requires access to a Sony Port100-class physical USB NFC device.
* The OOB read itself receives no corruption bonus: there is no write, UAF, disclosure path, or control-flow effect shown.
* Confidentiality was not awarded. Checksum validity may provide a weak behavioral oracle, but no adjacent bytes are returned or otherwise demonstrably disclosed.
* B5-R does not apply: this is a single read-only bounds failure, not a retry-accumulated heap OOB write followed by corrupted-state consumption.
* No authorization, shared-backing, or active-state trust-boundary primitive is present.
3. Reachability analysis
The evidenced attacker is a malicious physical USB device supplying a false frame length. No host account, UID 0, capability, namespace privilege, or prior privileged software configuration is needed after connection. NFC-radio remote reachability is not shown. The vulnerable check runs during ordinary response processing without a race or retry requirement.
4. Primitive and severity reading
The exact primitive is a device-controlled heap/URB-buffer OOB read in `port100_data_checksum()`. It may fault when reading beyond the transfer allocation, supporting host DoS, but there is no demonstrated disclosure, write, active structured-state corruption, or authorization bypass. This is therefore CLASS_C rather than a corruption-bearing Class A/B primitive. Important retention is unwarranted, and automatic downgrade is allowed.
5. One-sentence report phrase
A malicious Sony Port100 USB device can overstate a response length and make the NFC driver read beyond the received URB buffer, potentially crashing the host.
6. Manual review advice
MANUAL CHECK RECOMMENDED
Confirm the allocation-boundary fault behavior and whether any device-visible checksum response could expose a meaningful oracle.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: nfc: port100: reject frames whose declared length exceeds the received data
Commit: 0d482995f0cdd0302450aa300c684c642d8ab31f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0d482995f0cdd0302450aa300c684c642d8ab31f
Commit description:
port100_recv_response() passes the URB transfer buffer to
port100_rx_frame_is_valid(), which checksums le16_to_cpu(frame->datalen)
bytes of frame->data. datalen is a 16-bit field supplied by the device
and is never checked against the number of bytes actually received
(urb->actual_length), so a device reporting a datalen larger than the
received frame makes port100_data_checksum() read out of bounds past the
transfer buffer.
Reject a response whose declared frame size does not fit the received
length before validating it.
Found by 0sec ( https://0sec.ai ) using automated source analysis; the
missing bound is evident from source. Compile-tested.
Fixes: 562d4d5 ("NFC: Sony Port-100 Series driver")
Cc: [email protected]
Assisted-by: 0sec:claude-opus-4-8
Signed-off-by: Doruk Tan Ozturk <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: David Heidelberg <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
drivers/nfc/port100.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=0d482995f0cdd0302450aa300c684c642d8ab31f
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98481 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98481
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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