[CVE-2026-97510][LOW] thunderbolt: Release request if tb_cfg_request() fails in __tb_xdomain_response() [ Upstream

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

CVE: CVE-2026-97510
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: thunderbolt: Release request if tb_cfg_request() fails in __tb_xdomain_response() [ Upstream
Commit: 42dddadf6b6131af4d12bfa8bdc84ef954e8cef8
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=42dddadf6b6131af4d12bfa8bdc84ef954e8cef8
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97510
Analysis date: Thu, 24 Sep 2026 20:54:32 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

======================================================================
ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-97510 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97510

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: LOW
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-2026-97510	LOW	https://www.kernelcve.org/list/?q=CVE-2026-97510 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;CWE-703;Other CVSS 'AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.2';DESCR 'A memory leak in the Thunderbolt xdomain response path occurs when tb_cfg_request fails after a tb_cfg_request object has been allocated. The failure can happen when the control channel has already been shut down and the callback is not invoked to release the request. A malicious or unreliable Thunderbolt peer may contribute to this state through repeated device connection, disconnection, or control channel teardown events. For the CVSS the PR:N metric is used because no local account or privileges are required for a physically connected Thunderbolt peer to reach the protocol path. The attack vector is physical and repeated triggering is required to accumulate leaked allocations. Impact is denial of service through resource exhaustion. There is no evidence in the patch of memory corruption, information disclosure, integrity impact, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	YES	LEAK 	NO	NO	checked

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

ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: -1
* Conservative score: 0
* Raw paranoid score: -1
* Paranoid score: 0
* Applied lower bound: -1 -> 0
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Concrete persistent kernel resource leak. `tb_cfg_request_alloc()` allocates `req`, and a failing `tb_cfg_request()` does not invoke `response_ready`, so the normal callback-based release is skipped and the request reference is leaked.
* -2 Physical-only attack path. The affected xdomain control protocol is associated with a physically connected Thunderbolt peer. The supplied context does not establish a network-reachable or ordinary local-user trigger.
* No reliable kernel crash or strong DoS point. The patch establishes a leaked allocation, but does not establish that one or a small number of failures crashes the host.
* No additional resource-exhaustion point. Repeated accumulation sufficient for host-wide memory exhaustion is plausible but not established by the supplied call path.
* No memory corruption point. There is no free followed by use, stale dereference, double put, refcount mutation, out-of-bounds access, or overwrite.
* No confidentiality or integrity point. The missing `tb_cfg_request_put()` only loses a reference and does not expose or modify protected data.
* No local-unprivileged-trigger point. The complete device authorization and xdomain setup sequence is not visible.
* No remote-reachability point. Thunderbolt peer traffic is device and physical-fabric mediated, not direct network traffic.

3. Reachability analysis

The direct input source is a Thunderbolt xdomain peer. A failure of `tb_cfg_request()` can occur when the Thunderbolt control channel is already shut down, after which the allocated request is not released.

A malicious physical Thunderbolt device may potentially contribute to this state, for example around connection teardown or control-channel shutdown. However, the supplied code does not establish that an attacker can repeatedly create the required xdomain response and shutdown sequence, nor does it establish bypass of Thunderbolt authorization policy.

Host-admin-equivalent privilege is not positively required by the shown function, but below-host-admin reachability for the complete sequence is also not positively established. Therefore `HostAdminRequired=UNKNOWN`.

No namespace-scoped capability check or complete namespace-contained trigger is visible. Therefore `NamespaceScopedPrivilege=UNKNOWN`.

4. Primitive and severity interpretation

The exact primitive is a missing release of a newly allocated `struct tb_cfg_request` when `tb_cfg_request()` returns an error before accepting ownership and scheduling the completion callback.

This is a resource/reference leak, not an active structured-object UAF. The code performs one allocation and fails to perform its required cleanup. It does not release an object and later use or release the same dangling reference.

There is no concrete repeated release or refcount mutation. The first relevant lifetime operation is absent in the vulnerable code, and the fix adds the missing `tb_cfg_request_put()`. Therefore the repeated-release and real-UAF rules do not apply.

The demonstrated consequence is memory growth from leaked request objects. Host-wide resource exhaustion is only a conditional long-term possibility requiring repeated reachable failures. No exploitation leverage beyond resource consumption is established.

`PrimitiveClass=CLASS_C` is used because the practical security consequence is limited to a potential availability issue without a corruption, authorization, ownership-boundary, or stale-lifetime primitive. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` are appropriate because no unresolved meaningful corruption leverage remains.

5. One-sentence report phrase

A failed Thunderbolt xdomain request setup can leak a tb_cfg_request object because the completion callback is not invoked on error, potentially causing limited resource exhaustion after repeated physically mediated failures.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes a straightforward missing cleanup on an error path. No UAF, double release, refcount corruption, information disclosure, integrity impact, privilege escalation, or directly reachable remote attack path is shown.

7. Call-site confidence

Call-site confidence: medium

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

Patch: thunderbolt: Release request if tb_cfg_request() fails in __tb_xdomain_response() [ Upstream
Commit: 42dddadf6b6131af4d12bfa8bdc84ef954e8cef8
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=42dddadf6b6131af4d12bfa8bdc84ef954e8cef8

Changed files:
  drivers/thunderbolt/xdomain.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=42dddadf6b6131af4d12bfa8bdc84ef954e8cef8

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

The original Linux kernel CVE announcement for CVE-2026-97510 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97510

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:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.2

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).