[CVE-2026-53053][MODERATE 7.0] iommu/amd: Fix clone_alias() to use the original device's devid [ Upstream

[CVE-2026-53053][MODERATE 7.0] iommu/amd: Fix clone_alias() to use the original device's devid [ Upstream

[AL-KERNEL]

CVE: CVE-2026-53053
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: iommu/amd: Fix clone_alias() to use the original device's devid [ Upstream
Commit: dbd76a537d8cb814e7f5b795ab21ecb7949c821d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dbd76a537d8cb814e7f5b795ab21ecb7949c821d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53053
Analysis date: Wed, 24 Jun 2026 14:06:08 -0400
ActionableScore: 6
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum. Strong Important candidate if affected DMA alias or passthrough topology is confirmed
Manual review required: YES

Summary:
An AMD IOMMU alias handling bug may copy DTE state from the wrong PCI device, potentially propagating stale or incorrect DMA remapping entries to aliases and weakening DMA isolation on affected topologies.

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

The original Linux kernel CVE announcement for CVE-2026-53053 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53053

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-2026-53053	MODERATE	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:H/I:H/A:H';CWE-284;CWE-668;CWE-665;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'An AMD IOMMU alias handling logic bug can clone a device table entry from the wrong PCI device when pci_for_each_dma_alias supplies an alias device as the callback argument. This can propagate wrong or stale DTE state to DMA aliases and may weaken DMA isolation for affected PCI topologies. For the CVSS the PR:L reflects the paranoid case where a local actor controls a VM, service account, or delegated device management path that can exercise an affected DMA capable PCI device. The issue is not network reachable. Impact is not a normal kernel NULL dereference DoS. It may include denial of service through DMA faults and in the worst defensible case confidentiality or integrity impact if stale IOMMU mappings permit unintended DMA access.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum. Strong Important candidate if affected DMA alias or passthrough topology is confirmed (with actual score 5)	YES	SIMPLEFIX DMAorINTERRUPT HARDWARE  KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS	NO	NO	checked

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

ActionableScore=6
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 6
* Final recommended bucket: **Actionable Moderate at minimum. Strong Important candidate if affected DMA alias or passthrough topology is confirmed**::

## 2. Signal breakdown

Conservative signals:

* Firmware-mediated external influence: +1. The issue depends on PCI DMA alias topology and AMD IOMMU device table setup, which may be influenced by platform firmware or device enumeration rather than ordinary local input.
* Privileged kernel/device-management sensitive state: +1. The bug affects AMD IOMMU DTE propagation, which is security-sensitive DMA remapping state.
* Confidentiality impact plausible: +1. A wrong or stale DTE may theoretically weaken DMA isolation and expose memory that should not be reachable by a DMA-capable alias.
* Integrity impact plausible: +1. Incorrect DMA remapping may theoretically allow unintended DMA writes or corruption through an alias.
* Availability impact realistic: +1. Wrong DTE state can plausibly cause DMA faults, device malfunction, or host instability.
* Rare and topology-dependent condition: -1. The issue requires AMD IOMMU plus PCI DMA aliases in a topology where pci_for_each_dma_alias() passes an alias device in the callback.

Paranoid additions or interpretation:

* Security-boundary bypass with sensitive-object access: +2. If stale DTE state permits unintended DMA access, this becomes an IOMMU isolation bypass rather than a simple driver logic bug.
* No generic kernel memory corruption bonus is applied. The patch does not show UAF, OOB write, double free, type confusion, or attacker-controlled overwrite of ordinary kernel heap objects.
* No strong LPE bonus is applied. Privilege escalation is possible only indirectly through a DMA isolation failure scenario and is not demonstrated by the patch.

## 3. Reachability analysis

The bug is not network reachable. Triggering depends on AMD IOMMU setup for PCI devices with DMA aliases, typically during device initialization, hotplug, or device-management paths. In normal deployments, direct control over such paths usually requires host administrator privileges or physical or firmware-level influence. Namespaces and containers generally do not lower the privilege requirement because ordinary containers cannot control host PCI topology or IOMMU setup. A more concerning paranoid case exists for virtualization or passthrough environments where a reduced-privilege actor, VM, or service account can exercise a DMA-capable assigned device and rely on host-side alias handling.

## 4. Severity interpretation

This is not an ordinary Moderate if the affected topology is present, because the corrupted state is IOMMU DTE state and may affect DMA isolation. Realistically, the most likely observed impact is device failure, DMA faults, or host availability problems under specific hardware topology. The theoretical higher-impact case is confidentiality or integrity loss through stale or wrong DMA mappings, but the patch does not demonstrate a reliable attacker-controlled DMA access primitive or a direct privilege escalation chain. Therefore the conservative result is borderline/manual-review, while the paranoid result is Actionable Moderate and potentially Important if passthrough or hostile DMA-capable device scenarios are confirmed.

## 5. One-sentence report phrase

An AMD IOMMU alias handling bug may copy DTE state from the wrong PCI device, potentially propagating stale or incorrect DMA remapping entries to aliases and weakening DMA isolation on affected topologies.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED. The affected object is IOMMU DMA-remapping state, and wrong or stale DTE propagation can cross a hardware isolation boundary even though the patch does not prove a direct memory-corruption or LPE primitive.

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

Patch: iommu/amd: Fix clone_alias() to use the original device's devid [ Upstream
Commit: dbd76a537d8cb814e7f5b795ab21ecb7949c821d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dbd76a537d8cb814e7f5b795ab21ecb7949c821d

Changed files:
  drivers/iommu/amd/iommu.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=dbd76a537d8cb814e7f5b795ab21ecb7949c821d

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

The original Linux kernel CVE announcement for CVE-2026-53053 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53053

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:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 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: 6

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).