[CVE-2026-72150][MODERATE 7.0] sunrpc: fix uninitialized xprt_create_args structure

[CVE-2026-72150][MODERATE 7.0] sunrpc: fix uninitialized xprt_create_args structure

[AL-KERNEL]

CVE: CVE-2026-72150
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: sunrpc: fix uninitialized xprt_create_args structure
Commit: 933654508b2bc36e2c3c086c0365e2403fb2141f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=933654508b2bc36e2c3c086c0365e2403fb2141f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72150
Analysis date: Sun, 16 Aug 2026 03:38:23 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
An uninitialized `xprt_create_args` structure in the SUNRPC sysfs transport creation path may cause garbage pointer dereference, limited stack-data exposure, or unpredictable transport flags, leading primarily to local DoS and requiring manual review for possible confidentiality or integrity impact.

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

The original Linux kernel CVE announcement for CVE-2026-72150 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72150

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-72150	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';*CWE-457;CWE-824;**CWE-476;*CWE-200;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:H';BEST CVSS score: '5.8';DESCR 'An uninitialized xprt_create_args structure in rpc_sysfs_xprt_switch_add_xprt_store can leave fields such as srcaddr, bc_xps, and flags filled with stack garbage. The transport setup path may then dereference a garbage srcaddr, use unexpected flags, or expose unintended stack derived data, resulting in kernel panic or a limited information leak. For the CVSS the PR:L is used in the paranoid score because a local user or service with delegated write access to the SUNRPC sysfs control path could reach the store handler, while typical systems restrict this path to root or an administrator. The issue is not directly network reachable and requires local interaction with the SUNRPC sysfs control plane. Impact is at least local denial of service via kernel crash and in worst case may allow limited confidentiality or integrity impact due to use of uninitialized stack data.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	REMOTE INIT SIMPLEFIX LEAK NETWORK LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative scoring:

* Weak or indirect corruption candidate: +1. Uninitialized stack fields in `xprt_create_args` may be interpreted as pointers or flags by the transport setup path.
* Reliable kernel crash / strong DoS: +1. The commit explicitly states that `xs_setup_xprt()` may dereference garbage `srcaddr` and panic the kernel.
* Availability impact realistic: +1. A kernel panic is host-wide availability impact if the sysfs path is reachable.
* Confidentiality impact plausible: +1. The commit states that `srcaddr` may point to sensitive stack data, giving a limited information leak concern.
* Broad/common subsystem exposure: +1. SUNRPC/NFS is a common kernel subsystem on systems using NFS.
* Requires admin/root in typical deployments: -2. Writing the relevant SUNRPC sysfs control path is normally restricted to root or an administrator.
* Corruption primitive constrained / no attacker-controlled payload: -1. The attacker does not directly choose the stack garbage value or a controlled overwrite target.

Conservative total: 3

Paranoid scoring:

* Local unprivileged or reduced-privilege trigger concern: +1. In delegated sysfs, service-account, container-root, or reduced-capability setups, the store handler might be reachable without full host-root equivalence.
* Weak LPE concern: +1. Bogus pointer use and random flags create an invalid object interpretation sink, but no concrete reclaim, overwrite, callback control, or type confusion is shown.
* Weak or indirect corruption candidate: +1. Uninitialized stack data may influence pointer and flag handling.
* Reliable kernel crash / strong DoS: +1. Garbage `srcaddr` dereference can panic the kernel.
* Confidentiality impact plausible: +1. Stack-derived data may be exposed through transport setup behavior.
* Integrity impact plausible: +1. Random `flags` may cause unexpected behavior, but this remains weak and unproven.
* Hard or unreliable condition: -1. The exact value and usefulness of stack garbage are not attacker-controlled and may be non-deterministic.

Paranoid total: 5

## 3. Reachability analysis

The bug is triggered through `rpc_sysfs_xprt_switch_add_xprt_store()`, so realistic triggering requires local write access to the SUNRPC sysfs control plane. In normal deployments this is an administrator-only path, so the conservative interpretation applies a root/admin privilege penalty.

Namespaces or containers may matter if a reduced-privilege service, container root, or delegated management component can write the relevant sysfs node without full host-root equivalence. That supports the paranoid PR:L-style interpretation, but not a default PR:N interpretation.

The path is not directly network reachable. Network activity may be involved after transport creation, but the vulnerable operation is local control-plane interaction through sysfs.

Call-site confidence: medium. The patch is minimal, but the commit explicitly names downstream use in `xs_setup_xprt()` and identifies `srcaddr`, `bc_xps`, and `flags` as uninitialized fields with security-relevant consequences.

## 4. Severity interpretation

This is more than an ordinary Low issue because the affected structure contains pointer-like and behavior-controlling fields, and the commit explicitly describes kernel panic and possible stack-data exposure. However, it is not a Strong Important candidate by default because the patch does not show a controlled overwrite, UAF reclaim, type confusion, arbitrary write, callback hijack, or reliable privilege-escalation primitive.

Realistic impact is local privileged DoS with possible limited information leak. Paranoid handling is justified because uninitialized stack data can sometimes hide more serious behavior than a simple NULL dereference, but the evidence supports Actionable Moderate rather than Important.

## 5. One-sentence report phrase

An uninitialized `xprt_create_args` structure in the SUNRPC sysfs transport creation path may cause garbage pointer dereference, limited stack-data exposure, or unpredictable transport flags, leading primarily to local DoS and requiring manual review for possible confidentiality or integrity impact.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the bug involves uninitialized stack data used as pointer-like and flag fields, with an explicit kernel panic path and a plausible limited information leak concern. This should not be auto-closed even though typical triggering requires local administrative access.

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

Patch: sunrpc: fix uninitialized xprt_create_args structure
Commit: 933654508b2bc36e2c3c086c0365e2403fb2141f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=933654508b2bc36e2c3c086c0365e2403fb2141f

Commit description:

The xprt_create_args structure is allocated on the stack without
initialization in rpc_sysfs_xprt_switch_add_xprt_store(). While some
fields are manually populated, critical fields like srcaddr, bc_xps,
and flags contain uninitialized stack garbage.

This can lead to:
1. Kernel panic when xs_setup_xprt() dereferences garbage srcaddr
2. Information leak if srcaddr points to sensitive stack data
3. Unpredictable behavior if flags has random bits set

The fix is to zero-initialize the structure to ensure all unused
fields are NULL/0, preventing the transport setup code from acting
on garbage data.

Cc: stable@vger.kernel.org
Suggested-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>
Signed-off-by: Anna Schumaker <anna.schumaker@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/sunrpc/sysfs.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=933654508b2bc36e2c3c086c0365e2403fb2141f

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

The original Linux kernel CVE announcement for CVE-2026-72150 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72150

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:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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: 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).