[CVE-2026-64019][MODERATE REGULAR] nvme-pci: fix dma mapping leak on data setup error [ Upstream

[CVE-2026-64019][MODERATE REGULAR] nvme-pci: fix dma mapping leak on data setup error [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64019
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: nvme-pci: fix dma mapping leak on data setup error [ Upstream
Commit: e50db059ec8e63bc50b1cc039e2502cb5ea75a70
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e50db059ec8e63bc50b1cc039e2502cb5ea75a70
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64019
Analysis date: Sun, 19 Jul 2026 15:19:06 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Ordinary Moderate / Borderline Moderate, not Important
Manual review required: NO

Summary:
A local DMA mapping leak in the nvme-pci PRP/SGL setup error paths can exhaust DMA or IOVA resources under repeated failures, causing NVMe I/O degradation or denial of service without evidence of memory corruption or privilege escalation.

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

The original Linux kernel CVE announcement for CVE-2026-64019 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64019

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.

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

CVE-2026-64019	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	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-772;CWE-404;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A DMA mapping leak in the NVMe/PCI host driver can occur when data setup fails after the initial DMA iterator mapping was created but before the PRP or SGL tracking descriptor was allocated. The same class of leak can also happen when the PRP mapping path detects an invalid bio_vec after DMA mappings are already active. For the CVSS the PR:L is used because a local user or process that can generate I/O to the affected NVMe block device may be sufficient in some deployments, while reliable triggering still depends on setup error conditions such as allocation failure or malformed request state. The issue is not network reachable and does not provide a demonstrated memory corruption primitive. Impact is denial of service through DMA or IOVA resource exhaustion, I/O failures, or device degradation rather than confidentiality loss or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Borderline Moderate, not Important (with actual score 4)  SKIP CVE-2026-64019 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: b8b7570a7ec872f2a27b775c4f8710ca8a357adf YES  NO NO unknown 	MAYBE	INIT NVME LEAK DMAorINTERRUPT HARDWARE LINUS MEMORY  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=4
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 4
* Final recommended bucket: **Ordinary Moderate / Borderline Moderate, not Important**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local process that can generate I/O to an affected NVMe block device may reach the request mapping path, although reliable triggering depends on error conditions.
* Availability impact realistic: +1. Leaked DMA/IOVA mappings can accumulate and cause I/O failures, resource exhaustion, or device degradation.
* Broad/default/common subsystem: +1. nvme-pci is a common storage driver on Linux systems using NVMe PCI devices.
* Important filesystem/storage path: +1. The affected code is in the NVMe host data mapping path.
* Hard or unreliable trigger: -1. The leak requires allocation failure during PRP/SGL descriptor setup or an invalid bio_vec mapping path, so this is not a simple one-shot trigger.

Paranoid additional signal:

* Reliable kernel crash / strong DoS: +1. If an attacker can repeatedly force the setup error under memory pressure, DMA/IOVA resources may be exhausted until device reset or reboot.

Signals not applied:

* No generic memory corruption. The patch fixes missing unmap on error paths, not UAF, double-free, OOB write, type confusion, or arbitrary write.
* No privilege escalation plausible. There is no demonstrated reclaim, overwrite, stale callback, object confusion, or refcount takeover.
* No confidentiality or integrity impact. The described primitive is resource leakage, not data disclosure or unauthorized modification.
* No remote/network reachability. This is a local NVMe PCI host driver path, not NVMe/TCP or a network protocol parser.

Call-site confidence: high. The patch shows the affected PRP, SGL, metadata setup, and invalid PRP request cleanup paths.

## 3. Reachability analysis

A local user or local process can potentially trigger the affected path by generating I/O to an NVMe-backed block device, depending on filesystem permissions, block device access, and workload shape. Direct raw block access may require privileges, but ordinary filesystem I/O can still reach the NVMe request path in common deployments.

Namespaces and containers only matter if the container or sandbox can issue I/O to the affected storage device. This does not become PR:N because local code execution is required. The path is default-relevant on systems with NVMe PCI storage, but the vulnerable condition requires setup failure or malformed request state, so practical exploitation is less reliable than ordinary local DoS bugs.

## 4. Severity interpretation

This behaves more like an ordinary Moderate or Low-like resource exhaustion issue than an Important-class kernel vulnerability. The theoretical impact is local DoS through DMA/IOVA mapping leakage and storage degradation. Realistic exploitation evidence for privilege escalation or memory corruption is not present in the patch.

The paranoid score reaches 4 only because the affected subsystem is common and storage-critical, and sustained leakage could cause broader availability impact. It should not be treated as Important without additional evidence of memory corruption, attacker-controlled object lifetime, or privilege escalation.

## 5. One-sentence report phrase

A local DMA mapping leak in the nvme-pci PRP/SGL setup error paths can exhaust DMA or IOVA resources under repeated failures, causing NVMe I/O degradation or denial of service without evidence of memory corruption or privilege escalation.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a local resource leak without remote reachability, memory corruption, confidentiality impact, integrity impact, or plausible LPE primitive. Operational testing may be useful for NVMe-heavy systems, but security manual review is not required.

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

Patch: nvme-pci: fix dma mapping leak on data setup error [ Upstream
Commit: e50db059ec8e63bc50b1cc039e2502cb5ea75a70
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e50db059ec8e63bc50b1cc039e2502cb5ea75a70

Changed files:
  drivers/nvme/host/pci.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=e50db059ec8e63bc50b1cc039e2502cb5ea75a70

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

The original Linux kernel CVE announcement for CVE-2026-64019 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64019

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:L/UI:N/S:U/C:N/I:N/A:L
  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: 3
  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).