[CVE-2026-97540][MODERATE REGULAR] net: usb: pegasus: don't rely on id table pointer arithmetic [ Upstream

[CVE-2026-97540][MODERATE REGULAR] net: usb: pegasus: don't rely on id table pointer arithmetic [ Upstream

[AL-KERNEL]

CVE: CVE-2026-97540
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: net: usb: pegasus: don't rely on id table pointer arithmetic [ Upstream
Commit: 9425a13960ef38bac237608f25c9ee64ff113086
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9425a13960ef38bac237608f25c9ee64ff113086
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97540
Analysis date: Fri, 25 Sep 2026 12:42:08 -0400
ActionableScore: 1
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-2026-97540 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97540

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: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-97540	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97540 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:L/I:N/A:H';CWE-125;CWE-129;CWE-824;Other CVSS 'AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.8';DESCR 'A flaw in the pegasus USB Ethernet driver occurs because probe code calculates an array index by subtracting a dynamic USB ID pointer from the static pegasus_ids array. Dynamic IDs can be heap allocated, so the calculated index can be far outside the valid array range and later accesses can perform invalid reads or dereference an invalid name pointer during device initialization. A physically connected USB device can trigger the affected probe path if a matching dynamic ID was previously configured on the host. For the CVSS the PR:N is used because the physical attacker does not need an account or local code execution when that non default configuration already exists. The issue is not network reachable. Impact is at least denial of service through a kernel crash. The out of bounds read may also have limited confidentiality impact in the worst case, but the patch does not demonstrate a write primitive or a plausible privilege escalation path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	OOB USB NETWORK HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	NO	NO	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Weak indirect corruption candidate. `pegasus_probe()` computes `dev_index` by subtracting a heap allocated dynamic `usb_device_id` pointer from the static `pegasus_ids` array. The resulting index is invalid and is later used for reads from `usb_dev_id[dev_index]`.
* +1 Reliable kernel crash or strong DoS. The invalid index is used to read `private` and `name`. In particular, the `name` value is passed to `%s` in `dev_info()`, and an invalid pointer read or dereference can fault the kernel during device probe.
* -1 No attacker controlled payload or target. The invalid index derives from kernel heap versus static-array address arithmetic, not from an attacker selected index or controlled memory address. The patch does not establish a controlled kernel read target, a write target, or attacker shaped replacement contents.

Important non-awarded signals:

* Controlled reclaim is not demonstrated.
* Arbitrary or directed kernel write is not demonstrated.
* A real UAF is not established. The dynamic ID object is heap allocated, but the bug is invalid pointer arithmetic and out of bounds indexing, not use after free.
* Confidentiality is not awarded. The OOB data is consumed internally, and no reliable user visible disclosure path is established.
* Integrity is not awarded. The patch shows only reads from the invalid array index. Driver feature values may become incorrect, but no kernel memory write primitive is shown.
* Remote reachability is not established. The relevant trigger is USB device enumeration.
* Local unprivileged trigger is not awarded. The input does not establish that an ordinary local user can configure the required dynamic USB ID or complete the full trigger sequence.
* No physical hardware penalty is applied. A physical USB device or USB emulation path is required, but the evidence does not establish that the required hardware is rare enough for the rare hardware penalty.

3. Reachability analysis

The affected path is reached when the pegasus USB network driver probes a device matched through a dynamic USB ID. The commit explicitly states that a dynamic `usb_device_id` can reside on the heap, unlike entries in the static `pegasus_ids` array.

A physical attacker may be able to trigger probing by attaching a USB device that matches a preconfigured dynamic ID. However, the supplied material does not establish who can configure that dynamic ID in the evaluated deployment. Adding a dynamic ID through the generic USB driver interface may require elevated host-side privileges, while a separately preconfigured dynamic ID could allow a physical attacker to trigger the probe without an account on the host.

Therefore, HostAdminRequired is `UNKNOWN`. It is not proven that host administration is required for every triggering scenario, but below-host-admin control of the complete configuration and trigger chain is also not proven. NamespaceScopedPrivilege is `UNKNOWN` because no namespace-specific capability or complete namespaced trigger path is shown.

The issue is not network reachable. It requires USB enumeration and a matching dynamic ID. No race, boot parameter, firmware compromise, or special device DMA behavior is required by the patch evidence.

4. Primitive and severity interpretation

The exact primitive is an invalid out of bounds array index caused by pointer arithmetic between unrelated objects. `id - pegasus_ids` is valid only when `id` points into the static ID table. For dynamic IDs, `id` may point to heap storage, causing `dev_index` to be wildly out of range.

The invalid index is used for reads of fields from `usb_dev_id[dev_index]`, including the device name passed to a string formatting path and feature flags used during initialization. This can produce an invalid pointer dereference and a kernel crash.

This is neither an active structured-object UAF nor fixed stale storage. There is no release, refcount decrement, stale post-lifetime access, second lifetime mutation, controlled replacement, callback consumption, or post-free field processing. There is also no demonstrated arbitrary read, arbitrary write, type confusion, ownership violation, authorization bypass, or privilege escalation mechanism.

The issue is therefore `CLASS_C`. The demonstrated practical consequence is kernel DoS during probe. A limited information disclosure possibility exists only as a theoretical concern because an unintended pointer may be interpreted as a string, but the patch does not establish a usable disclosure channel. ImportantCandidate is `NO` because the available evidence supports a constrained invalid-read and crash condition rather than meaningful unresolved exploitation leverage. AutoDowngradeAllowed is `YES` because no active lifetime, memory-write, authorization, ownership, or boundary-bypass primitive remains unresolved.

5. One-sentence report phrase

A malformed dynamic USB ID can cause the pegasus driver to calculate an out of bounds table index during device probe and potentially crash the kernel when invalid data is dereferenced.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm whether the target product permits non-administrative configuration of USB dynamic IDs, whether matching dynamic IDs are deployed in practice, and whether kernel logs expose any useful output from the invalid name pointer path.

7. Call-site confidence

Call-site confidence: medium

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

Patch: net: usb: pegasus: don't rely on id table pointer arithmetic [ Upstream
Commit: 9425a13960ef38bac237608f25c9ee64ff113086
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9425a13960ef38bac237608f25c9ee64ff113086

Changed files:
  drivers/net/usb/pegasus.c
  drivers/net/usb/pegasus.h

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=9425a13960ef38bac237608f25c9ee64ff113086

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

The original Linux kernel CVE announcement for CVE-2026-97540 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97540

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:H
  The Best / paranoid CVSS vector: AV:P/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 4.8

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: 1

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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).