[CVE-2026-99107][MODERATE 7.0] ntfs: fix incorrect MFT record pointer passed to ntfs_attr_record_resize

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

CVE: CVE-2026-99107
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: ntfs: fix incorrect MFT record pointer passed to ntfs_attr_record_resize
Commit: 0a9122cada749447dfb6d67aa3fed4ee1982231c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0a9122cada749447dfb6d67aa3fed4ee1982231c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99107
Analysis date: Thu, 29 Oct 2026 00:14:59 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
A writable NTFS extent attribute can be resized against the wrong MFT record, producing invalid `memmove` bounds and a plausible kernel out-of-bounds corruption path.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-99107 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99107

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-2026-99107	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-99107 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=MODERATE_KPANIC RESULT=SAME (final reconciliation agrees; DECISION: both MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-125;CWE-682;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'ntfs_new_attr_flags can pass a base MFT record to ntfs_attr_record_resize even when the attribute is stored in an extent record referenced by ctx mrec. The resize helper then calculates memmove bounds using a record that does not contain the attribute, creating a plausible out of bounds read and write that may crash the kernel or corrupt adjacent kernel memory. For the CVSS the PR:L value reflects that reliable triggering normally requires a local user or process with write access to a suitable mounted NTFS filesystem. AC:H reflects the requirement for a specific extent record layout and an EA or reparse operation that reaches this resize path. The issue is not directly network reachable. Privilege escalation is not proven, but the concrete memory corruption primitive supports manual investigation and a paranoid HHH impact assessment. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 7 and the production ActionableScore returned 5 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage LOW to MODERATE_KPANIC because the ActionableScore threshold rule was applied. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were INCREASED_TO_MODERATE7_FROM_LOW_BASED_ON_GUESSCVSS_AND_ACTIONABLESCOREHIGHER4. The independent weaker Aegis shadow evaluated CVSS 3.1 and ActionableScore 2 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)	MAYBE	DISK SIMPLEFIX LEAK LINUS  KPANIC INCREASED_TO_MODERATE7_FROM_LOW_BASED_ON_GUESSCVSS_AND_ACTIONABLESCOREHIGHER4	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 5.
* Conservative score: 5; no floor or cap applied.
* Raw paranoid score: 5.
* Paranoid score: 5; stronger heap-OOB or exploitation claims lack sufficient helper/allocation context.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +1 weak/indirect corruption candidate: an extent attribute `a` is resized using the unrelated base record `m`; the commit confirms this produces incorrect `memmove` size calculations.
* +1 local unprivileged trigger: supplied evidence grounds the path in a process with write access to a suitable mounted NTFS filesystem, without host-administrator powers for the runtime EA/reparse operation.
* +1 filesystem metadata corruption concern: the faulty resize modifies an MFT attribute record.
* +1 important filesystem/storage path: MFT record sizing and movement govern active NTFS metadata.
* +1 plausible kernel crash/strong DoS: a cross-record `memmove` length can access outside the intended record.
* No additional availability point; it would duplicate the same possible crash.
* No Class-A OOB-write bonus: the supplied helper body, allocation boundaries, exact write range, and overwritten object are absent. The legacy summary itself calls the OOB read/write “plausible.”
* No confidentiality, arbitrary write, controlled target, LPE, or protected-object corruption is proven.
* B5-R does not apply: no retry-accumulated index or retry sequence exists.
* B4-PENDING does not apply: no authorization decision is changed.

3. Reachability analysis

A local process able to modify EA/reparse metadata on a writable NTFS inode can plausibly reach the operation. A writable NTFS mount is prior system setup, but the runtime trigger is not shown to require UID 0 or an administrative capability. No namespace capability is involved. The extent-record layout raises complexity, but no timing race is shown.

4. Primitive and severity reading

The primitive is a wrong-container pointer supplied to an active metadata resize helper, causing `memmove` bounds to be calculated from the base MFT record while the attribute resides in an extent record. This is a strong Class-B memory-layout/corruption candidate. An actual heap/slab OOB write is likely but not fully confirmed from the one-line patch alone. Crash and metadata corruption are plausible; adjacent-object corruption and exploitation remain unresolved. Mandatory review is warranted because auto-downgrading would discard a concrete cross-record write-length defect.

5. One-sentence report phrase

A writable NTFS extent attribute can be resized against the wrong MFT record, producing invalid `memmove` bounds and a plausible kernel out-of-bounds corruption path.

6. Manual review advice

MANUAL CHECK REQUIRED

Confirm `ntfs_attr_record_resize()` pointer arithmetic, record allocation boundaries, exact write range, and whether attacker-shaped extent layouts can corrupt adjacent active kernel objects.

7. Call-site confidence

Call-site confidence: medium

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

Patch: ntfs: fix incorrect MFT record pointer passed to ntfs_attr_record_resize
Commit: 0a9122cada749447dfb6d67aa3fed4ee1982231c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0a9122cada749447dfb6d67aa3fed4ee1982231c

Commit description:

ntfs_new_attr_flags() passes the wrong MFT record to ntfs_attr_record_resize().
When the attribute is in an extent record, ctx->mrec points to the extent
but the function receives the base record pointer m, causing incorrect
size calculations in memmove.

Fix by passing ctx->mrec (the actual MFT record containing the attribute)
instead of m (the base MFT record) to ntfs_attr_record_resize().

Fixes: fc053f0 ("ntfs: add reparse and ea operations")
Cc: stable@vger.kernel.org
Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  fs/ntfs/ea.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=0a9122cada749447dfb6d67aa3fed4ee1982231c

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

The original Linux kernel CVE announcement for CVE-2026-99107 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99107

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