[CVE-2026-45877][LOW] HID: intel-ish-hid: fix NULL-ptr-deref in ishtp_bus_remove_all_clients [ Upstream

[CVE-2026-45877][LOW] HID: intel-ish-hid: fix NULL-ptr-deref in ishtp_bus_remove_all_clients [ Upstream

[AL-KERNEL]

CVE: CVE-2026-45877
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: HID: intel-ish-hid: fix NULL-ptr-deref in ishtp_bus_remove_all_clients [ Upstream
Commit: 0b605e8ce60698c27a26f512968a597fd620d2e8
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0b605e8ce60698c27a26f512968a597fd620d2e8
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45877
Analysis date: Wed, 27 May 2026 23:29:18 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
An Intel ISH warm-reset race can leave an ISHTP client without a device pointer and trigger a NULL pointer dereference during client removal, causing local kernel DoS.

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

The original Linux kernel CVE announcement for CVE-2026-45877 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45877

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-2026-45877	LOW	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-362;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'A warm reset race in intel-ish-hid can leave an ISHTP client with cl device still NULL while ishtp_bus_remove_all_clients() checks the client reference count. A local or platform reset path can then dereference the NULL device pointer and crash the kernel. For the CVSS the PR:L is used in the paranoid score because some systems may expose firmware update, warm reset, reboot stress, or power management flows to service accounts below full host root, while reliable triggering usually requires privileged platform control. The issue is not network reachable. Impact is denial of service through kernel panic. No supported evidence indicates information disclosure, integrity impact, kernel memory corruption, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) 	MAYBE	KASAN NULLPTR USB SIMPLEFIX HARDWARE BOOT TEST 	-	-	checked

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

ActionableScore=2
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

* Reliable kernel crash / strong DoS: +1
  The trace shows a NULL pointer dereference in `ishtp_bus_remove_all_clients()` during warm reset handling.

* Availability impact realistic: +1
  The realistic impact is kernel panic or local platform DoS during warm reset or firmware reset.

* Local delegated platform/reset trigger: +1 in paranoid scoring
  Some systems may expose reboot, firmware update, warm reset, or power-management flows to service accounts.

* Requires privileged or platform-driven reset in typical deployments: -2 conservative
  Reliable triggering usually requires firmware reset, warm reboot stress, or platform/driver reset control.

* Rare/hardware-specific subsystem: -1 conservative
  This affects Intel ISH / intel-ish-hid systems and a specific reset/enumeration timing condition.

* No memory corruption: +0
  This is a NULL pointer dereference, not UAF, OOB write, arbitrary write, or controlled memory corruption.

* No remote reachability: +0
  The issue is local/platform reset-path driven, not network reachable.

## 3. Reachability analysis

The bug is reachable during Intel ISH warm reset or firmware reset while ISHTP clients are still being enumerated. In normal deployments, reliable triggering is tied to platform reset, firmware update, reboot stress, or privileged device/power-management operations. Namespaces do not materially reduce the requirement unless reset or firmware update controls are exposed to a less trusted service.

The issue is not network reachable. Realistic exploitation is DoS-only.

## 4. Severity interpretation

This behaves like Low or ordinary Moderate availability impact. The issue is a real kernel crash path but hardware-specific and reset-timing dependent. There is no evidence of memory corruption, information disclosure, integrity impact, or privilege escalation.

## 5. One-sentence report phrase

An Intel ISH warm-reset race can leave an ISHTP client without a device pointer and trigger a NULL pointer dereference during client removal, causing local kernel DoS.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

The issue is a hardware-specific NULL dereference in a privileged or platform-driven reset path, with no memory corruption, remote reachability, or privilege escalation evidence.

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

Patch: HID: intel-ish-hid: fix NULL-ptr-deref in ishtp_bus_remove_all_clients [ Upstream
Commit: 0b605e8ce60698c27a26f512968a597fd620d2e8
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0b605e8ce60698c27a26f512968a597fd620d2e8

Changed files:
  drivers/hid/intel-ish-hid/ishtp/bus.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=0b605e8ce60698c27a26f512968a597fd620d2e8

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

The original Linux kernel CVE announcement for CVE-2026-45877 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45877

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:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: 0
  Paranoid ActionableScore: 2

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).