[CVE-2026-98760][MODERATE 7.0] usb: typec: tipd: fix uninitialized typec_partner_desc in tps6598x_connect()

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

CVE: CVE-2026-98760
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: usb: typec: tipd: fix uninitialized typec_partner_desc in tps6598x_connect()
Commit: 4b6823ce0e548491cb9663303cba28e18d351096
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4b6823ce0e548491cb9663303cba28e18d351096
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98760
Analysis date: Sat, 24 Oct 2026 12:50:34 -0400
ActionableScore: 3
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
A physical Type-C connection can persist uninitialized stack values as partner callbacks that are later invoked in the kernel, plausibly crashing the host and exposing limited stack-derived sysfs values.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-98760 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98760

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 7.0
Manual review required: YES

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
======================================================================

CVE-2026-98760	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98760 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=3 LEGACY=MODERATE_KPANIC RESULT=SAME V39_AEGIS_ONE_STEP_UP=MODERATE->MODERATE_KPANIC (final reconciliation agrees; DECISION: both MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-457;CWE-908;CWE-824;*CWE-200;Other CVSS 'AV:P/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H';BEST CVSS score: '6.4';DESCR 'An uninitialized stack allocated typec_partner_desc can copy garbage attach and deattach callback pointers into a Type C partner. A later USB device link can invoke one of these pointers and cause an invalid indirect kernel call, with kernel crash as the most credible impact. Uninitialized pd_revision and usb_capability values can also disclose limited stack data through partner sysfs attributes. For the CVSS the PR:N value is used because a physically connected USB Type C device does not need an authenticated local user context. The base score does not claim reliable code execution because attacker control over the stale callback address is not established. The paranoid score accounts for potential kernel control flow compromise if the stack layout makes the callback value influenceable. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 6.4 and the production ActionableScore returned 3 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage LOW to MODERATE_KPANIC because the manual review requirement was applied. ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold rule was applied. final reconciliation stage MODERATE to MODERATE_KPANIC because the cross model evidence reconciliation 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 INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK and DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 4.8 and ActionableScore 3 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 3)	MAYBE	USB SIMPLEFIX LEAK HARDWARE  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 KPANIC V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED	-	-	checked

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

ActionableScore=3
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 3.
* Conservative score: 3; no floor or cap applied.
* Raw paranoid score: 3.
* Paranoid score: 3; no additional attacker control over stack contents is established.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +2 active structured pointer corruption: uninitialized stack values are copied into persistent `attach` and `deattach` callback fields, which are later invoked indirectly.
* +1 firmware/device-mediated external trigger: Type-C connection and subsequent USB-device linking can create and consume the corrupted partner state.
* +1 reliable kernel crash concern: invocation of a garbage callback address plausibly causes an invalid indirect kernel call.
* +1 limited confidentiality impact: the commit explicitly states that uninitialized `pd_revision` and `usb_capability` reach partner sysfs.
* -2 physical-access prerequisite: exercising the device-driven path requires a physically connected USB Type-C device.

Not awarded: arbitrary or attacker-directed callback address, controlled stack shaping, reliable code execution, LPE, or high-integrity impact. The callback corruption is not a UAF or OOB write. No extra availability point is added for the same crash.

3. Reachability analysis

A physically attached Type-C device can induce partner connection, and a later USB-device link invokes the copied callback. This does not require host UID 0, host-administrator capability, or namespace capability. The supplied evidence does not show remote reachability or attacker control over the stale stack bytes. No special rare hardware is shown beyond the physical Type-C prerequisite.

4. Primitive and severity reading

The primitive is an uninitialized-data corruption of active structured state: garbage kernel-stack values become stored function pointers and are later consumed by a privileged kernel indirect-call site. This is CLASS_B because the dangerous callback consumption is concrete, but attacker influence over the callback value or target is not demonstrated. A kernel crash and limited sysfs disclosure are supported; controlled execution and privilege escalation remain speculative.

ImportantCandidate is YES because a real corrupted callback crosses the physical-device/host-kernel trust boundary and is actively consumed. Auto-downgrade is disallowed pending review of stack-layout influence and callback reachability.

5. One-sentence report phrase

A physical Type-C connection can persist uninitialized stack values as partner callbacks that are later invoked in the kernel, plausibly crashing the host and exposing limited stack-derived sysfs values.

6. Manual review advice

MANUAL CHECK REQUIRED

Review whether preceding stack contents can be influenced and whether either callback invocation can produce controllable indirect control flow rather than only a fault.

7. Call-site confidence

Call-site confidence: high

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

Patch: usb: typec: tipd: fix uninitialized typec_partner_desc in tps6598x_connect()
Commit: 4b6823ce0e548491cb9663303cba28e18d351096
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4b6823ce0e548491cb9663303cba28e18d351096

Commit description:

tps6598x_connect() passes a stack-allocated typec_partner_desc to
typec_register_partner() after initializing only usb_pd, accessory and
identity.

typec_register_partner() copies attach and deattach from the descriptor
into the partner. With those fields left unset, garbage function pointers
may be stored and later invoked from typec_partner_link_device() when a USB
device is linked to the port. Uninitialized pd_revision and usb_capability
similarly leak stack data through partner sysfs.

Zero-initialize the descriptor so optional callbacks remain NULL and the
remaining fields are zero.

Fixes: 0a4c005 ("usb: typec: driver for TI TPS6598x USB Power Delivery controllers")
Cc: stable <stable@kernel.org> # 5.15+
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Link: https://patch.msgid.link/20260906131942.83153-2-radhey.shyam.pandey@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/usb/typec/tipd/core.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=4b6823ce0e548491cb9663303cba28e18d351096

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

The original Linux kernel CVE announcement for CVE-2026-98760 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98760

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:H/PR:N/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS vector: AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.4

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: 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: YES
Published priority for this report (same as in Subject): MODERATE 7.0

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).