* [CVE-2026-98238][MODERATE REGULAR] net: wwan: t7xx: validate the netif index in t7xx_ccmni_recv_skb()
@ 2026-10-09 9:47 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-10-09 9:47 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98238
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: net: wwan: t7xx: validate the netif index in t7xx_ccmni_recv_skb()
Commit: 7c2fe308bda5a7e6222d7f0c3c311991372baab4
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7c2fe308bda5a7e6222d7f0c3c311991372baab4
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98238
Analysis date: Fri, 09 Oct 2026 05:47:38 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98238 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98238
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-2026-98238 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98238 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (independent 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:L/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-129;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: '7.6';DESCR 'The t7xx WWAN receive path trusts the five bit netif index from the DPMAIF PIT header even though ccmni_inst contains only 21 entries. Values from 21 through 31 cause an out of bounds array read into the adjacent callback table. The resulting non NULL value is then treated as a struct t7xx_ccmni pointer and dereferenced during skb processing, which can cause a kernel crash and may route the skb through invalid driver state. For the CVSS the PR:N is used because no local host user context is required when a malicious or compromised modem can supply the malformed DPMAIF metadata. The base assessment uses AV:P because the demonstrated trigger requires a fault injector or control of the attached modem side. The paranoid assessment uses AV:A because the modem is logically adjacent to the host over DPMAIF, but direct triggering by an arbitrary remote cellular peer is not established. Impact is at least denial of service via an invalid kernel pointer dereference. Limited confidentiality or integrity impact is considered in the paranoid score because the invalid pointer reaches further skb processing, but no arbitrary write or reliable privilege escalation primitive is demonstrated.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) MAYBE WRITE OOB SIMPLEFIX NETWORK SKB LINUS PACKET DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 2
* Conservative score: 2
* 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 or indirect corruption candidate. An unchecked index reads beyond `ccmni_inst[]`, and the resulting value is interpreted as a `struct t7xx_ccmni` pointer.
* +1 Firmware-mediated external influence. The invalid index originates in a DPMAIF PIT header supplied through the modem-facing receive path.
* +1 Reliable kernel crash or strong DoS concern. The invalid non-NULL pointer is dereferenced and reaches subsequent skb processing, making a kernel fault realistic.
* -1 No attacker-controlled payload or target is established. The index selects among a small number of adjacent callback-table entries, but control of those pointer values, a write destination, or replacement contents is not shown.
Paranoid difference:
* The -1 constraint is withheld because the invalid structured pointer is consumed deeply enough to queue the skb rather than being rejected or guaranteed to fault immediately. This does not add a strong corruption primitive, but containment is not positively established.
Important non-awarded signals:
* B5-R does not apply. There is no confirmed heap or slab OOB write and no retry-accumulated index or offset.
* A read-only OOB access is established, followed by invalid structured-object interpretation.
* No arbitrary or directed write is demonstrated.
* No controlled type confusion, callback invocation, controlled reclaim, UAF, disclosure, or privilege escalation is demonstrated.
* Direct remote reachability from a cellular peer is not established because modem or firmware mediation is material.
* No confidentiality point is awarded because no data is returned to userspace, the network, or another observable sink.
* No integrity point is awarded merely because an skb reaches invalid driver state.
* No extra availability point is awarded because it would duplicate the same potential kernel crash.
3. Reachability analysis
The demonstrated trigger uses a QEMU fault injector to set `netif_idx` to 25. In a physical deployment, malformed metadata must arrive from the t7xx modem or its firmware. A compromised or malicious modem could plausibly provide this value, but the supplied evidence does not establish that ordinary over-the-air traffic can directly control the DPMAIF index.
No host userspace privilege is needed once malformed metadata is delivered to the receive path. However, the evidence does not establish how an attacker obtains control over that metadata without fault injection, firmware compromise, or device control. Therefore `HostAdminRequired` remains `UNKNOWN`.
The operation is not based on a namespace-scoped capability or namespace-local control-plane API, so `NamespaceScopedPrivilege=NO`. No race or retry sequence is involved. Specialized t7xx hardware or an emulated equivalent is required, but no rare-hardware penalty is applied merely because the bug is in a device driver.
4. Primitive and severity interpretation
The exact primitive is a bounded OOB read from `ccmni_inst[21..31]`. The read lands in an adjacent callback table, producing a non-NULL kernel pointer that is incorrectly interpreted as `struct t7xx_ccmni`. Fields reached through that bogus pointer are then used during active skb processing.
This is not a UAF, lifetime violation, repeated release, or OOB write. It is broader than a harmless invalid read because the resulting pointer affects later processing, but no independently useful write, disclosure, callback control, or authorization bypass is established. It therefore remains `CLASS_C`.
The demonstrated practical consequence is invalid-state processing and a plausible kernel crash. Limited non-crash effects are conceivable because the skb can be queued using invalid state, but the supplied evidence does not establish a security-useful consequence. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` are appropriate because no unresolved Class A or strong Class B primitive exists.
5. One-sentence report phrase
An unchecked modem supplied interface index causes an out of bounds pointer read and invalid t7xx object dereference during skb processing, creating a firmware mediated kernel crash risk without a demonstrated write, disclosure, or privilege escalation primitive.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Review should determine whether real modem firmware or over-the-air input can control `netif_idx`, and whether downstream skb processing through the bogus `ccmni` pointer performs any write or externally observable disclosure before faulting.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: net: wwan: t7xx: validate the netif index in t7xx_ccmni_recv_skb()
Commit: 7c2fe308bda5a7e6222d7f0c3c311991372baab4
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7c2fe308bda5a7e6222d7f0c3c311991372baab4
Commit description:
The netif index carried in the DPMAIF PIT header is five bits wide,
but ccmni_inst[] only has room for NIC_DEV_MAX (21) entries.
t7xx_ccmni_recv_skb() indexes the array without a bounds check, so
indexes 21 to 31 read past it. The out-of-bounds value lands in the
callback table that follows the array, which is never NULL, so the
existing !ccmni check does not catch it and the driver dereferences
whatever sits there as a struct t7xx_ccmni.
Drop the skb when the index is out of range.
Fixes: 05d19bf ("net: wwan: t7xx: Add WWAN network interface")
Cc: [email protected]
Signed-off-by: Guanglei Zhu <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Changed files:
drivers/net/wwan/t7xx/t7xx_netdev.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=7c2fe308bda5a7e6222d7f0c3c311991372baab4
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98238 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98238
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:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
The Best / paranoid CVSS score: 7.6
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: 2
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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