[CVE-2026-99098][MODERATE 7.0] dm-integrity: fix buffer overflow in inline mode with large tag size [ Upstream

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

CVE: CVE-2026-99098
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: dm-integrity: fix buffer overflow in inline mode with large tag size [ Upstream
Commit: 3c7aad85aeb9e28386672e3a009aa2e61f751b86
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c7aad85aeb9e28386672e3a009aa2e61f751b86
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99098
Analysis date: Mon, 26 Oct 2026 22:35:21 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: YES

Summary:
A host administrator can configure an oversized dm-integrity inline tag that causes zero padding beyond a stack digest buffer and reliably panics stack-protected kernels.

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

The original Linux kernel CVE announcement for CVE-2026-99098 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99098

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-2026-99098	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-99098 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE_KPANIC RESULT=SAME V39_AEGIS_ONE_STEP_UP=MODERATE->MODERATE_KPANIC (final reconciliation agrees; DECISION: both MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H';CWE-121;*CWE-787;CWE-131;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.7';DESCR 'dm-integrity inline mode uses an on-stack digest buffer that was limited to HASH_MAX_DIGESTSIZE while integrity_sector_checksum can zero pad the result up to the configured tag size. A tag larger than the buffer therefore provides a concrete stack out-of-bounds zero write and CONFIG_STACKPROTECTOR causes a kernel panic on the first read. For the CVSS the PR:H value is selected because reliably creating the affected Device Mapper configuration requires root or equivalent administrative control. Availability impact is confirmed while confidentiality and integrity impact remain a worst case concern because stack corruption exists but controlled code execution or privilege escalation is not demonstrated. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 6.7 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold rule was applied. final reconciliation stage MODERATE to MODERATE_KPANIC because the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 4.4 and ActionableScore 1 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	MAYBE	OOB DANGER DISK SIMPLEFIX KERNEL_PANIC_PLUS_UAF LINUS MEMORY  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 KPANIC V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED	-	-	checked

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

ActionableScore=1
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=YES
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 1 (+2 attacker-influenced stack OOB write, +1 reliable kernel panic, -2 proven host-administrator requirement).
* Conservative score: 1; no floor or cap applied.
* Raw paranoid score: 1; theoretical code execution, confidentiality, and integrity effects are unsupported.
* Paranoid score: 1.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +2 — Concrete stack out-of-bounds write: `integrity_sector_checksum()` zero-pads through the configured tag size, while the old destination is only `HASH_MAX_DIGESTSIZE`. The administrator-selected tag size controls the overwrite extent.
* +1 — Reliable kernel crash: the commit reports stack-protector panic on the first read.
* -2 — Complete trigger requires root or equivalent Device Mapper administration, positively stated by the commit and supplied evidence.
* No additional availability point: it would duplicate the same panic.
* No C/I points: the payload is zero padding, and no controlled return-address value, disclosure, LPE, or useful adjacent target is shown.
* B5-R does not apply: there is no retry-accumulated index or re-entry sequence.
* B3-PENDING and B4-PENDING do not apply: no shared backing write or authorization decision is involved.

3. Reachability analysis

The trigger requires creating/configuring a dm-integrity inline target with an unusually large tag size, which the supplied evidence identifies as requiring root or equivalent host Device Mapper authority. No user-namespace, delegated capability, ordinary-user, or remote path is shown. There is no race or special hardware prerequisite.

4. Primitive and severity reading

The primitive is an attacker-sized, zero-filled stack OOB write, not a UAF. It is CLASS_A technically because a configured length drives a confirmed write beyond a stack object. The shown consequence is a stack-canary panic; useful corruption or privilege gain is unproven. ImportantCandidate remains YES and auto-downgrade is disabled for the concrete strong write primitive, but the proven host-administrator-only trigger makes the practical severity ordinary Moderate rather than an Important vulnerability.

5. One-sentence report phrase

A host administrator can configure an oversized dm-integrity inline tag that causes zero padding beyond a stack digest buffer and reliably panics stack-protected kernels.

6. Manual review advice

MANUAL CHECK REQUIRED

Confirm that no supported Device Mapper delegation permits a below-host-admin actor to create or modify the affected target.

7. Call-site confidence

Call-site confidence: high

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

Patch: dm-integrity: fix buffer overflow in inline mode with large tag size [ Upstream
Commit: 3c7aad85aeb9e28386672e3a009aa2e61f751b86
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c7aad85aeb9e28386672e3a009aa2e61f751b86

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=3c7aad85aeb9e28386672e3a009aa2e61f751b86

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

The original Linux kernel CVE announcement for CVE-2026-99098 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99098

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:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.7

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: MODERATE
KPANIC detected for this report: YES
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).