[CVE-2026-72465][MODERATE 7.0] xprtrdma: Sanitize the reply credit grant after parsing [ Upstream

[CVE-2026-72465][MODERATE 7.0] xprtrdma: Sanitize the reply credit grant after parsing [ Upstream

[AL-KERNEL]

CVE: CVE-2026-72465
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: xprtrdma: Sanitize the reply credit grant after parsing [ Upstream
Commit: 7cf332b3d82d73ffceedca6b4a120be074172021
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7cf332b3d82d73ffceedca6b4a120be074172021
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72465
Analysis date: Sat, 15 Aug 2026 18:01:57 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A malicious RPC/RDMA peer can send replies with unknown XIDs and inflated credit grants, causing the client to allocate and post receive resources beyond the configured request limit and potentially trigger denial of service.

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

The original Linux kernel CVE announcement for CVE-2026-72465 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72465

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-2026-72465	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';**CWE-400;CWE-770;*CWE-20;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '6.5';DESCR 'An RPC over RDMA reply handler consumed an untrusted credit grant before it was clamped when the reply did not match any pending request. A malicious or compromised RDMA peer can send a well formed reply with an unknown XID and an inflated credit grant, causing the client to post and allocate receive resources beyond re_max_requests. For the CVSS the PR:N is used because the attacker does not need privileges on the victim once the RDMA peer path is reachable. The attack is not typical public Internet exposure and is more relevant to NFS/RDMA or RPC over RDMA deployments inside storage or data center networks. Impact is denial of service through memory or RDMA receive resource exhaustion. No confidentiality or integrity impact is assigned because the patch indicates a boundedness failure in resource posting, not UAF, OOB write, or information disclosure.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)  SKIP CVE-2026-72465 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 704f3f640f72db4d44ec5ce3db8d4e150c974bc7 YES  NO NO unknown 	MAYBE	REMOTE DEADLOCK SIMPLEFIX NETWORK  DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	-	-	checked

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

ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

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

## 2. Signal breakdown

Conservative signals:

* +2 Remote reachable / network-triggerable: a malicious or compromised RPC/RDMA peer can send a well formed reply with unknown XID and inflated credit grant.
* +1 Reliable kernel crash / strong DoS: unbounded receive posting and allocation can exhaust receive resources or memory.
* +1 Availability impact realistic: repeated replies can drive allocations past `re_max_requests` until allocation or RDMA receive resource failure.
* +1 Important filesystem/storage path: this affects SUNRPC xprtrdma, commonly used for NFS/RDMA storage transport.
* -1 Rare AND difficult-to-reach subsystem/configuration: RPC over RDMA / NFS/RDMA is not a default Internet-facing path and usually exists inside storage or data-center fabrics.

Paranoid difference:

* The paranoid score keeps the same technical class but does not subtract the full rarity penalty, because exposed NFS/RDMA storage fabrics can make the peer-triggered DoS operationally important.

No memory corruption, UAF, OOB write, info leak, or privilege escalation primitive is supported by the patch.

## 3. Reachability analysis

The bug can be triggered by a peer able to send RPC/RDMA replies to the affected client. The attacker does not need local privileges on the victim, so PR:N is reasonable for CVSS once the RDMA peer path is reachable. This is not typical public Internet exposure. It is mainly relevant to NFS/RDMA or RPC over RDMA deployments in storage, HPC, or data-center networks. Namespaces are not the main factor here because the vulnerable path is in the kernel client transport receiving peer replies.

## 4. Severity interpretation

This behaves like an actionable network-adjacent resource exhaustion issue, not an Important-class memory corruption vulnerability. The demonstrated impact is DoS through uncontrolled receive buffer allocation and posting. Theoretical escalation is not supported because the patch only shows missing bounds enforcement on a wire-supplied credit value, with no evidence of stale pointer reuse, overwrite, UAF, or information disclosure.

## 5. One-sentence report phrase

A malicious RPC/RDMA peer can send replies with unknown XIDs and inflated credit grants, causing the client to allocate and post receive resources beyond the configured request limit and potentially trigger denial of service.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the issue is peer-triggerable over a storage network and can cause resource exhaustion with high availability impact in affected NFS/RDMA deployments, so it should not be auto-closed even though it is not a memory corruption or privilege escalation bug.

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

Patch: xprtrdma: Sanitize the reply credit grant after parsing [ Upstream
Commit: 7cf332b3d82d73ffceedca6b4a120be074172021
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7cf332b3d82d73ffceedca6b4a120be074172021

Changed files:
  net/sunrpc/xprtrdma/rpc_rdma.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=7cf332b3d82d73ffceedca6b4a120be074172021

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

The original Linux kernel CVE announcement for CVE-2026-72465 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72465

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:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 6.5

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: 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: NO
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).