[CVE-2026-72467][LOW] xprtrdma: Check frwr_wp_create() during connect [ Upstream

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

CVE: CVE-2026-72467
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: xprtrdma: Check frwr_wp_create() during connect [ Upstream
Commit: 3b252fe1778b2cdd68283146455929801bc2abd7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3b252fe1778b2cdd68283146455929801bc2abd7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72467
Analysis date: Sat, 15 Aug 2026 02:51:40 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-72467 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72467

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: LOW
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-2026-72467	LOW	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	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-252;**CWE-476;CWE-754;BEST CVSS score: '4.7';DESCR 'An unchecked frwr_wp_create() failure in the xprtrdma connect path can leave the client transport marked connected while the write-pad MR pointer is NULL. A later NFS/RDMA read with a non-4-byte-aligned receive length can reach rpcrdma_encode_write_list() and dereference that NULL MR through encode_rdma_segment(), causing a kernel crash. For the CVSS the PR:L is used for the paranoid score because a local unprivileged process that can access an existing NFS/RDMA mount may trigger reads and reconnect activity, while the required local MR allocation, DMA map, MR map, or post-send failure makes the attack high complexity. The issue is not directly network reachable. A remote NFS/RDMA peer alone is not expected to trigger the fault because the critical failure is local to the client. Impact is denial of service only, with no supported UAF, OOB access, information leak, or privilege escalation primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	REMOTE NETWORK  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	guess

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

ActionableScore=1

1. ActionableScore
* Conservative score: 1
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**::

2. Signal breakdown
* Local unprivileged trigger: +1. A local process that can access an existing NFS/RDMA mount may trigger reads and reconnect activity.
* Reliable kernel crash / strong DoS: +1. If the NULL write-pad MR state is reached, a later unaligned NFS/RDMA read can dereference NULL and crash the kernel.
* Hard or unreliable race / special condition required: -1. The trigger depends on a local MR allocation, DMA-map, MR-map, or post-send failure during connect or reconnect.
* Rare AND difficult-to-reach subsystem/configuration: -1. NFS/RDMA requires RDMA-capable deployment and is not a broad default client path.
* Paranoid addition: +1 availability/exposure concern because the failure can crash the client kernel once the bad connected state is published.

3. Reachability analysis
The bug is local to an NFS/RDMA client. A remote peer alone cannot force the local MR setup failure according to the commit message. A local user may trigger NFS/RDMA reads on an already mounted filesystem, but creating the mount or controlling RDMA setup is typically administrative. Namespaces do not meaningfully lower this unless an environment delegates access to an existing NFS/RDMA mount. The path is not default-enabled on ordinary systems and requires NFS over RDMA plus a local connect/reconnect failure.

4. Severity interpretation
This behaves like an ordinary Moderate or Low-like kernel DoS issue rather than an Important vulnerability. The demonstrated primitive is NULL pointer dereference, not UAF, OOB write, refcount misuse, stale callback, arbitrary write, or page-cache corruption. Realistic exploitation evidence supports kernel crash only, with high complexity due to the required local MR setup failure.

5. One-sentence report phrase
Unchecked frwr_wp_create() failure can leave an NFS/RDMA client transport connected with a NULL write-pad MR, allowing a later local unaligned read path to crash the kernel under specific reconnect failure conditions.

6. Manual review recommendation
NO MANUAL CHECK NEEDED.
The issue is DoS-only, non-network-triggerable by the peer alone, configuration-dependent, and lacks a supported memory corruption or privilege escalation primitive.

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

Patch: xprtrdma: Check frwr_wp_create() during connect [ Upstream
Commit: 3b252fe1778b2cdd68283146455929801bc2abd7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3b252fe1778b2cdd68283146455929801bc2abd7

Changed files:
  net/sunrpc/xprtrdma/verbs.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=3b252fe1778b2cdd68283146455929801bc2abd7

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

The original Linux kernel CVE announcement for CVE-2026-72467 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72467

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: Not available
  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: 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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).