* [CVE-2026-98583][MODERATE REGULAR] nfc: nfcmrvl: validate helper command length before pull [ Upstream
@ 2026-10-24 0:11 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-24 0:11 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98583
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: nfc: nfcmrvl: validate helper command length before pull [ Upstream
Commit: 842c0603cfa49530ef081f181a2ddbba77a37231
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=842c0603cfa49530ef081f181a2ddbba77a37231
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98583
Analysis date: Fri, 23 Oct 2026 20:11:27 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
A truncated nfcmrvl firmware helper response can be read before its complete length is validated, causing a limited invalid skb read and a possible sanitizer fault or denial of service, while direct triggering by an ordinary NFC peer remains unproven.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98583 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98583
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: YES
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-98583 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98583 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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';CWE-125;*CWE-20;CWE-1285;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'The nfcmrvl firmware download receive path removes the NCI data header and reads skb data before confirming that the complete helper command is present. A truncated frame can therefore cause an invalid read beyond the logical packet data before the malformed command is rejected. For the CVSS the PR:N value is used because no authenticated local user context is required if an attacker can influence frames delivered by the NFC controller. AV:A and AC:H reflect that the target must use the affected driver, enter the firmware download state, and receive a specially truncated helper response. This is not an IP network vulnerability, and direct triggering by an ordinary remote NFC peer is not established because the command normally comes from the controller firmware path. The demonstrated impact is limited to an invalid read, with possible warning or denial of service on hardened systems. There is no supported UAF, out of bounds write, information disclosure path, or privilege escalation primitive. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 5.3 and the production ActionableScore returned 2 with recommendation Borderline / manual review recommended. 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 3.1 and ActionableScore 1 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 Borderline / manual review recommended (with actual score 2) MAYBE DANGER SIMPLEFIX SKB LINUS PACKET DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 3
* Paranoid score: 3
* No floor or cap was applied.
* Final recommended bucket: **Borderline / manual review recommended**::
2. Signal breakdown
Conservative signals:
* +1 Weak invalid-read concern. After `skb_pull()` the code reads `skb->data[0]` before proving that the complete NCI header and five-byte helper command are present.
* No negative points. Hardware rarity, host-admin privilege, and difficult attacker reachability are not positively established.
Paranoid additions:
* +1 Firmware-mediated external influence. The malformed response enters through the NFC controller firmware-download receive path, although control by an ordinary radio peer is not established.
* +1 Potential kernel DoS. A read beyond the logical skb payload can produce a sanitizer fault or panic under hardened configurations. This is possible rather than demonstrated.
Not awarded:
* No OOB write, UAF, double release, arbitrary write, disclosure path, authorization bypass, or privilege-escalation primitive is established.
* Confidentiality is not awarded because the byte is only compared with a constant and is not returned to an attacker.
* NEW52 B5-R does not apply. There is no write, retry-accumulated offset, or later consumption of corrupted structured state.
* NEW53 B3-PENDING does not apply. No shared-backing write exists.
* V32, V33, and V34 do not apply. No attacker-controlled checksum placement or active-state write is present.
* B4-PENDING does not apply because no DENY-to-ALLOW authorization decision exists.
* No additional availability point is awarded for the same possible fault.
3. Reachability analysis
The affected path processes helper responses while the `nfcmrvl` device is downloading firmware. A malformed short frame must reach the host from the NFC controller in this specific state.
The supplied evidence does not establish that an ordinary over-the-air NFC peer can directly construct this helper response. A faulty, modified, or malicious controller or firmware is a more credible source, but the exact attacker-controlled transport chain is unresolved. This is not an IP-network-reachable path.
No user-namespace or network-namespace capability path is shown. No local ioctl or ordinary-user interface for injecting the helper response is established. Host-admin privilege is therefore UNKNOWN rather than YES or NO. Special `nfcmrvl` hardware and the firmware-download state are prerequisites, but no rarity penalty is applied without stronger deployment evidence. There is no race.
4. Primitive and severity interpretation
The exact primitive is a limited read beyond the logical skb payload. If `skb_pull()` cannot remove the requested header, its return value is ignored. If the pull succeeds but leaves insufficient data, `skb->data[0]` is still evaluated before the old length check.
This is not an active structured-state corruption, shared-backing modification, lifetime violation, or retry-accumulated overwrite. No state is written through the invalid access. The demonstrated consequence is malformed-packet processing followed by `-EINVAL`. A sanitizer report or kernel panic is a defensible worst case, but it is not demonstrated by the patch.
PrimitiveClass is CLASS_C because the behavior is an invalid read with possible crash impact and no independently useful corruption primitive. ImportantCandidate is NO because no write, disclosure, authorization bypass, or unresolved cross-boundary corruption chain exists. AutoDowngradeAllowed is YES because the remaining uncertainty concerns reachability and possible DoS, not an Important-preserving primitive.
Likely operational severity is Low, with a Borderline manual-review classification only to confirm whether affected hardware permits an untrusted NFC peer or another below-host-admin actor to inject firmware helper responses.
5. One-sentence report phrase
A truncated nfcmrvl firmware helper response can be read before its complete length is validated, causing a limited invalid skb read and a possible sanitizer fault or denial of service, while direct triggering by an ordinary NFC peer remains unproven.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Confirm whether an untrusted radio peer, userspace interface, or assigned device can influence helper responses during firmware download. If responses can originate only from trusted controller firmware, the issue can be handled as a low-priority robustness defect.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: nfc: nfcmrvl: validate helper command length before pull [ Upstream
Commit: 842c0603cfa49530ef081f181a2ddbba77a37231
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=842c0603cfa49530ef081f181a2ddbba77a37231
Changed files:
drivers/nfc/nfcmrvl/fw_dnld.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=842c0603cfa49530ef081f181a2ddbba77a37231
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98583 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98583
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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 5.3
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: 1
Paranoid ActionableScore: 3
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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