* [CVE-2026-98759][MODERATE 7.0] usb: typec: tipd: fix uninitialized typec_partner_desc in cd321x_update_work()
@ 2026-10-24 15:59 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-24 15:59 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98759
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: usb: typec: tipd: fix uninitialized typec_partner_desc in cd321x_update_work()
Commit: 75dc6cb377efd2f4428b7f76d3a590a0bbc10399
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=75dc6cb377efd2f4428b7f76d3a590a0bbc10399
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98759
Analysis date: Sat, 24 Oct 2026 11:59:42 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES
Summary:
A physical USB interaction can cause uninitialized stack values to become active Type-C partner callbacks later invoked by the kernel, with limited stack disclosure and unresolved callback-corruption impact.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98759 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98759
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-98759 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98759 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=4 LEGACY=MODERATE_KPANIC RESULT=SAME (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-824;*CWE-200;Other CVSS 'AV:P/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '6.4';DESCR 'cd321x_update_work used a stack allocated typec_partner_desc without initializing all fields. Garbage values in attach and deattach could be copied into the Type C partner and later invoked as kernel function pointers when a USB device is linked to the port. Uninitialized pd_revision and usb_capability could also expose limited kernel stack data through partner sysfs attributes. For the CVSS the PR:N value is selected because triggering through physical USB attachment does not require an authenticated software account or existing privileges on the target. AV:P reflects the need to interact with an affected CD321x Type C port. AC:H reflects that useful control of residual stack values is not demonstrated. The established impacts are a possible kernel crash and limited information exposure. The kernel context indirect callback provides a plausible but unproven integrity or privilege escalation path for the paranoid score. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 6.4 and the production ActionableScore returned 4 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 ActionableScore threshold rule was applied. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were INCREASED_TO_MODERATE7_FROM_LOW_BASED_ON_GUESSCVSS_AND_ACTIONABLESCOREHIGHER4. The independent weaker Aegis shadow evaluated CVSS 4.8 and ActionableScore 4 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The shadow agreed with the final production impact and aggregation did not change that impact. 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 4) MAYBE USB SIMPLEFIX LEAK HARDWARE KPANIC INCREASED_TO_MODERATE7_FROM_LOW_BASED_ON_GUESSCVSS_AND_ACTIONABLESCOREHIGHER4 - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=4
ActionableScoreLower=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: 4.
* Paranoid score: 4; no floor or cap applied.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
* +1 firmware/device-mediated external influence: physical USB attachment drives partner creation and later device linking.
* +1 weak/indirect kernel corruption: uninitialized stack values are copied into active `typec_partner` callback fields.
* +1 weak exploit leverage: `attach`/`deattach` garbage pointers are later invoked in privileged kernel context. Their values are not shown attacker-controlled.
* +1 reliable crash concern: invoking an invalid residual pointer plausibly causes a kernel fault.
* +1 confidentiality: uninitialized `pd_revision` and `usb_capability` are exposed through partner sysfs, providing a limited stack-data disclosure path.
* -2 physical-only trigger: supplied evidence requires interaction with an affected CD321x Type-C port.
* Paranoid +1: the concrete active callback corruption is consumed across the physical-device-to-host-kernel trust boundary; non-crash integrity consequences remain unresolved.
Not awarded: controlled payload or callback target, arbitrary write, controlled reclaim, UAF, LPE, remote reachability, or high confidentiality/integrity. No additional availability point is assigned for the same crash.
3. Reachability analysis
A physical actor can attach/link a USB device without a software account, UID 0, or host capability. The affected CD321x hardware and port are prerequisites. No namespace capability, prior privileged setup, or timing race is shown. Useful control over residual stack contents is not established.
4. Primitive and severity reading
The primitive is initialization failure followed by copying uninitialized callback pointers into an active heap-resident partner object and subsequently invoking them. This is CLASS_B active structured-state corruption, not a UAF and not a proven controlled function-pointer overwrite.
The callback invocation and limited sysfs disclosure are shown; code execution, chosen targets, and privilege escalation are speculative. ImportantCandidate is YES under the active-state/trust-boundary rule because the write, privileged consumer, and physical-device boundary are specific while final integrity leverage is unknown. Therefore automatic downgrade is unsafe.
B4 authorization review does not apply: no DENY-to-ALLOW security decision exists.
5. One-sentence report phrase
A physical USB interaction can cause uninitialized stack values to become active Type-C partner callbacks later invoked by the kernel, with limited stack disclosure and unresolved callback-corruption impact.
6. Manual review advice
MANUAL CHECK REQUIRED
Review stack-layout influence, callback invocation conditions, sysfs disclosure width, and whether device-controlled sequencing can improve pointer-value control.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: usb: typec: tipd: fix uninitialized typec_partner_desc in cd321x_update_work()
Commit: 75dc6cb377efd2f4428b7f76d3a590a0bbc10399
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=75dc6cb377efd2f4428b7f76d3a590a0bbc10399
Commit description:
cd321x_update_work() 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: 82432bb ("usb: typec: tipd: Handle mode transitions for CD321x")
Cc: stable <[email protected]> # 6.18+
Reviewed-by: Heikki Krogerus <[email protected]>
Signed-off-by: Radhey Shyam Pandey <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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=75dc6cb377efd2f4428b7f76d3a590a0bbc10399
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98759 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98759
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:L/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: 3
Paranoid ActionableScore: 4
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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