[CVE-2026-72101][MODERATE REGULAR] dm-integrity: fix leaking uninitialized kernel memory [ Upstream

[CVE-2026-72101][MODERATE REGULAR] dm-integrity: fix leaking uninitialized kernel memory [ Upstream

[AL-KERNEL]

CVE: CVE-2026-72101
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: dm-integrity: fix leaking uninitialized kernel memory [ Upstream
Commit: 50af3e51dc709384701dbc721b4bd865285c5f2c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=50af3e51dc709384701dbc721b4bd865285c5f2c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72101
Analysis date: Sun, 16 Aug 2026 08:47:58 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline manual review recommended
Manual review required: YES

Summary:
dm-integrity inline mode may leak uninitialized kernel memory because padding between tag_size and tuple_size was not zeroed before integrity metadata was used or stored.

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

The original Linux kernel CVE announcement for CVE-2026-72101 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72101

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-2026-72101	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:H/I:N/A:N';CWE-908;*CWE-200;CWE-665;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.5';DESCR 'dm-integrity inline mode can leak uninitialized kernel memory because the padding area between tag_size and tuple_size is not actually zeroed. The memset length is computed as tuple_size minus tuple_size, so no bytes are cleared before the integrity payload is used. For the CVSS the PR:L is used in the paranoid score if a local user or service can trigger I/O on the dm-integrity device and later read the affected metadata or device image. The issue is not network reachable and requires local access to a system using dm-integrity inline mode. Impact is information disclosure only, with no evidence of memory corruption, privilege escalation, or denial of service.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended (with actual score 2)	YES	DISK SIMPLEFIX LEAK HARDWARE LINUS  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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

ActionableScore=3
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Borderline manual review recommended**::

## 2. Signal breakdown

Conservative signals:

* Confidentiality impact plausible: +1. The bug is explicitly an uninitialized kernel memory disclosure in dm-integrity inline metadata.
* Important filesystem/storage path: +1. The affected code is in device-mapper integrity handling.
* Rare or configuration-dependent mode: -1. The issue requires dm-integrity inline mode with tag_size smaller than tuple_size.

Paranoid additional signal:

* Local unprivileged trigger: +1. If a local user or service can generate I/O on an affected dm-integrity-backed device and later access the exposed integrity metadata, practical leakage may be possible.

Not awarded:

* No generic memory corruption. The patch fixes a zero-length memset and does not show OOB write, UAF, double free, or type confusion.
* No privilege escalation signal. The primitive is information disclosure only.
* No remote reachability. This is a local storage stack issue.
* No DoS signal. The patch does not indicate crash, hang, or filesystem shutdown.

## 3. Reachability analysis

The bug is reachable only on systems using dm-integrity inline mode where tag_size is smaller than tuple_size. Triggering the affected path requires I/O through the dm-integrity device. Practical exploitation depends on whether the leaked integrity payload bytes are observable by the attacker, for example through raw block access, backup images, lower-layer device access, or delegated storage access. In typical deployments, creating or inspecting dm-integrity metadata is administrative, but a less privileged local user may still be able to trigger I/O through a filesystem placed on top of the device.

## 4. Severity interpretation

This behaves like an information disclosure issue, not memory corruption. The theoretical impact is kernel memory disclosure from uninitialized bytes in the integrity tuple padding. Realistic severity depends heavily on whether an attacker can read the affected metadata or backing storage. It is not an Important-class candidate by itself, but it should not be blindly auto-closed without checking deployment exposure.

## 5. One-sentence report phrase

dm-integrity inline mode may leak uninitialized kernel memory because padding between tag_size and tuple_size was not zeroed before integrity metadata was used or stored.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED.

Review should confirm whether affected systems use dm-integrity inline mode and whether non-admin users or services can observe the integrity metadata or underlying storage image.

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

Patch: dm-integrity: fix leaking uninitialized kernel memory [ Upstream
Commit: 50af3e51dc709384701dbc721b4bd865285c5f2c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=50af3e51dc709384701dbc721b4bd865285c5f2c

Changed files:
  drivers/md/dm-integrity.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=50af3e51dc709384701dbc721b4bd865285c5f2c

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

The original Linux kernel CVE announcement for CVE-2026-72101 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72101

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:L/PR:H/UI:N/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
  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: 1
  Paranoid ActionableScore: 3

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).