[CVE-2026-72487][MODERATE REGULAR] PCI: Check ROM header and data structure addr before accessing [ Upstream

[CVE-2026-72487][MODERATE REGULAR] PCI: Check ROM header and data structure addr before accessing [ Upstream

[AL-KERNEL]

CVE: CVE-2026-72487
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: PCI: Check ROM header and data structure addr before accessing [ Upstream
Commit: cd5b242d5848369b9e957340a7e30adee7b6763d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cd5b242d5848369b9e957340a7e30adee7b6763d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72487
Analysis date: Sat, 15 Aug 2026 17:15:14 -0400
ActionableScore: 4
ActionableScore lower bound: 2
Actionable bucket: Borderline Moderate, manual review recommended but not Important
Manual review required: YES

Summary:
A malformed PCI Expansion ROM can cause `pci_get_rom_size()` to perform an out-of-bounds or unaligned IOMEM read during ROM parsing, leading to a local kernel crash when the ROM is accessed.

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

The original Linux kernel CVE announcement for CVE-2026-72487 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72487

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: YES

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

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

CVE-2026-72487	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-125;*CWE-20;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A malformed PCI Expansion ROM can make pci_get_rom_size read the PCI data structure pointer near the end of the mapped ROM window or at an address that is not naturally aligned for readl(). This can cause an out of bounds IOMEM read or an alignment fault and crash the kernel when the ROM is read through the PCI ROM path. For the CVSS the PR:L is used for the paranoid score because reliable triggering may be possible for a local user or service that has delegated access to read PCI ROM data, while normal systems usually restrict this path to an administrator. The issue is not network reachable and requires local interaction with a PCI device ROM or a malformed device supplied ROM image. Impact is denial of service via kernel crash. No confidentiality or integrity impact is assigned because the observed primitive is an invalid read used for validation and not an information leak or write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Moderate, manual review recommended but not Important (with actual score 3)	YES	OOB DANGER KERNEL_PANIC_PLUS_UAF HARDWARE  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	NO	NO	checked

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

ActionableScore=4
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 4
* Final recommended bucket: **Borderline Moderate, manual review recommended but not Important**

## 2. Signal breakdown

Conservative signals:

* Firmware-mediated external influence: +1
  The malformed data comes from PCI Expansion ROM contents, which are device or firmware supplied.
* Reliable kernel crash / strong DoS: +1
  The commit shows real crashes on x86_64 and arm64 through `pci_get_rom_size()` when `readl(pds)` reads past the mapped ROM window or from an unaligned IOMEM address.
* Broad/default/common subsystem: +1
  PCI core ROM handling is a common kernel subsystem, though this exact ROM-read path is not commonly exposed to untrusted users.
* Requires admin/root/CAP_* in typical deployments: -2
  Reading PCI ROM through sysfs is normally restricted to root or administrative contexts.
* Availability impact realistic: +1
  The failure is a host kernel crash, not just a warning or recoverable error.

Paranoid adjustment:

* Local low-privilege/delegated trigger concern: +1
  If a service, container helper, diagnostic tool, or delegated local user can read PCI ROM data, the practical PR may be lower than full host root.
* Physical/firmware-specific malformed ROM precondition: -1
  Triggering requires a broken or malicious PCI ROM image or device-supplied ROM contents.
* No generic memory corruption bonus
  The primitive shown is an invalid read / alignment fault causing crash. There is no demonstrated write, UAF, type confusion, reclaim, callback control, or information disclosure.

## 3. Reachability analysis

The direct trigger is reading a PCI device ROM, e.g. through the `pci_read_rom()` sysfs path shown in the call trace. In normal deployments this is local and privileged, typically root-only. It is not network reachable.

Namespaces and containers do not normally expose raw PCI ROM access to unprivileged users, but the paranoid interpretation considers systems where hardware diagnostics, device passthrough management, or reduced-privilege services are allowed to access PCI ROM files. Exploitation also depends on a malformed device ROM or firmware-controlled ROM contents, so this is not a broadly triggerable local syscall bug.

Call-site confidence: high, because the call trace and patch show the concrete path `pci_read_rom()` -> `pci_map_rom()` -> `pci_get_rom_size()`.

## 4. Severity interpretation

This behaves like an ordinary-to-borderline Moderate kernel DoS. The demonstrated impact is a kernel crash from an out-of-bounds IOMEM read or unaligned IOMEM read. The patch does not support privilege escalation, arbitrary memory corruption, attacker-controlled overwrite, or data disclosure.

The paranoid score is higher because the input is firmware/device supplied and the crash is in trusted PCI core code, but the bug remains constrained to validation failure and crash prevention. It should not be treated as an Important-class vulnerability without additional evidence of unprivileged ROM access or a stronger corruption primitive.

## 5. One-sentence report phrase

A malformed PCI Expansion ROM can cause `pci_get_rom_size()` to perform an out-of-bounds or unaligned IOMEM read during ROM parsing, leading to a local kernel crash when the ROM is accessed.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is a kernel OOB IOMEM read with confirmed crash potential in PCI core code, but current evidence supports DoS only and typical triggering requires privileged local access plus malformed device ROM contents.

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

Patch: PCI: Check ROM header and data structure addr before accessing [ Upstream
Commit: cd5b242d5848369b9e957340a7e30adee7b6763d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cd5b242d5848369b9e957340a7e30adee7b6763d

Changed files:
  drivers/pci/rom.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=cd5b242d5848369b9e957340a7e30adee7b6763d

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

The original Linux kernel CVE announcement for CVE-2026-72487 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72487

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:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: 2
  Paranoid ActionableScore: 4

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).