[CVE-2026-68325][MODERATE 7.0] iommu/amd: Bound the early ACPI HID map [ Upstream

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

CVE: CVE-2026-68325
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: iommu/amd: Bound the early ACPI HID map [ Upstream
Commit: 1e31d2394e0db69541b1591d46c5ad6431c81db3
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1e31d2394e0db69541b1591d46c5ad6431c81db3
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68325
Analysis date: Mon, 10 Aug 2026 16:05:03 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
An unchecked `ivrs_acpihid` kernel command-line parser in AMD IOMMU early initialization could append more than four entries to a fixed map and cause a boot-time kernel out-of-bounds write, requiring boot-parameter control and mainly posing a crash or constrained memory-corruption risk.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-68325 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68325

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
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CVE-2026-68325	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-129;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H';BEST CVSS score: '6.7';DESCR 'The ivrs_acpihid kernel command line parser in the AMD IOMMU code appended entries to a fixed size early_acpihid_map without rejecting entries beyond the four element capacity. Supplying more than four ivrs_acpihid mappings can cause an out of bounds write during early boot initialization, which may corrupt adjacent kernel data or crash the system before normal operation. For the CVSS the PR:H is used because reliable triggering normally requires administrative control over the kernel command line, bootloader configuration, kexec flow, or an equivalent boot control path. The issue is not network reachable and is not exposed through normal packet or syscall input after boot. Impact is at least denial of service during boot and in the paranoid interpretation may include broader confidentiality or integrity impact because the primitive is a kernel out of bounds write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	SIMPLEFIX  KPANIC INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Memory corruption, strong corruption primitive: +2. The parser can write past a fixed four element `early_acpihid_map` array.
* Privileged kernel/device-management memory corruption path: +1. The corruption occurs in AMD IOMMU early initialization code.
* Reliable kernel crash / strong DoS: +1. An early boot OOB write can realistically crash or prevent boot.
* Integrity impact plausible: +1. Adjacent early kernel state may be corrupted by an OOB write, although no controlled target is shown.
* Requires admin/root/boot control in typical deployments: -2. Triggering requires control over the kernel command line, bootloader, kexec path, or equivalent boot configuration.
* Corruption primitive constrained or target not demonstrated: -1. The patch shows an OOB write, but not attacker-selected overwrite target, reclaim, type confusion, or arbitrary write.

Paranoid adjustment:

* Confidentiality impact plausible: +1. Because this is a real kernel OOB write in early trusted initialization, broader memory corruption impact is defensible for manual triage, even though no disclosure primitive is demonstrated.

## 3. Reachability analysis

The bug is triggered through the `ivrs_acpihid` kernel command-line parameter during early boot. It is not network reachable and is not exposed through a normal runtime syscall, packet path, netlink interface, or device ioctl after boot.

In typical deployments, an attacker needs administrative control over boot parameters, bootloader configuration, kexec, provisioning metadata, or equivalent host management access. Containers and ordinary namespaces generally do not reduce the privilege requirement, unless the environment delegates boot parameter control to a less trusted management layer.

The path is configuration-dependent on AMD IOMMU and use of the `ivrs_acpihid` parameter. However, the primitive is an actual fixed-array OOB write in early kernel code, so it should not be treated as a pure validation cleanup.

Call-site confidence: high. The changed code directly guards the fixed-size map before parsing and storing another entry.

## 4. Severity interpretation

This behaves more like an actionable Moderate than an ordinary Low/Moderate issue because the patch fixes a concrete out-of-bounds write in kernel early initialization. The realistic exploitation model is limited by the high privilege requirement and boot-time-only trigger, which prevents an Important rating in the conservative interpretation.

The theoretical memory corruption potential is real, but practical privilege escalation is weak because the attacker usually already controls boot configuration. No remote trigger, unprivileged local trigger, reclaim primitive, type confusion, callback control, or arbitrary write target is demonstrated.

## 5. One-sentence report phrase

An unchecked `ivrs_acpihid` kernel command-line parser in AMD IOMMU early initialization could append more than four entries to a fixed map and cause a boot-time kernel out-of-bounds write, requiring boot-parameter control and mainly posing a crash or constrained memory-corruption risk.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the issue is gated by high privileges, but it is still a real kernel OOB write in early IOMMU initialization, so it should not be auto-closed without confirming the adjacent object layout and practical impact.

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

Patch: iommu/amd: Bound the early ACPI HID map [ Upstream
Commit: 1e31d2394e0db69541b1591d46c5ad6431c81db3
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1e31d2394e0db69541b1591d46c5ad6431c81db3

Changed files:
  drivers/iommu/amd/init.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=1e31d2394e0db69541b1591d46c5ad6431c81db3

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

The original Linux kernel CVE announcement for CVE-2026-68325 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68325

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:L/PR:H/UI:N/S:U/C:N/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.7

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: 4
  Paranoid ActionableScore: 5

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).