[CVE-2026-98445][LOW] xfs: don't let memory failures leak blocks and kill repairs [ Upstream

[CVE-2026-98445][LOW] xfs: don't let memory failures leak blocks and kill repairs [ Upstream

[AL-KERNEL]

CVE: CVE-2026-98445
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: xfs: don't let memory failures leak blocks and kill repairs [ Upstream
Commit: 3380151cf0ce8ad0c1d356fed51e4b69e1d28e50
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3380151cf0ce8ad0c1d356fed51e4b69e1d28e50
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98445
Analysis date: Sat, 24 Oct 2026 09:47:25 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
An administratively invoked XFS online repair can leak staged-btree blocks and shut down the filesystem if a small reservation-record allocation fails.

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

The original Linux kernel CVE announcement for CVE-2026-98445 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98445

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: LOW
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-98445	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98445 CHECK WITH IMPACT FROM ORIG NN NONE | AEGIS IMPACT MODERATE AEGIS_AS=1 LEGACY=LOW RESULT=DIFF (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H';CWE-404;*CWE-772;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'An allocation failure in xrep_newbt_add_blocks can occur after XFS online repair has allocated blocks for a staged btree. The caller cannot both undo all transaction changes and return ENOMEM, so the failure can leak allocated filesystem blocks and can terminate repair or shut down the affected filesystem. This is a resource retention and error handling issue with no supported UAF, OOB access, arbitrary write, or information disclosure primitive. For the CVSS the PR:H value reflects that reliably reaching this path normally requires administrative authority to start XFS online repair. AC:H reflects the additional need to make a small kernel allocation fail at the relevant point. The issue is local and is not directly reachable through ordinary filesystem I O or network traffic. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were final reconciliation stage LOW to LOW 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 V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	DISK NOMEMCHK SIMPLEFIX LEAK LINUS  V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED	-	-	checked

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

ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 0 (+1 persistent block/resource leak, +1 filesystem shutdown/strong DoS, +1 important filesystem repair path, -2 host-administrator privilege, -1 difficult targeted allocation failure).
* Conservative score: 0; no floor or cap applies.
* Raw paranoid score: 0; no technically supported additional primitive.
* Paranoid score: 0.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Concrete persistent resource leak: failure to allocate the reservation record loses tracking of blocks already allocated for the staged btree.
* +1 Strong DoS: the transaction error-handling limitation can terminate repair or shut down the filesystem.
* +1 Important filesystem path: the defect affects XFS online-repair block reservation/accounting.
* -2 Host-admin-equivalent privilege: supplied evidence states that initiating the complete online-repair path normally requires administrative authority.
* -1 Hard trigger condition: failure must occur during a small, approximately 48-byte kernel allocation at the relevant point.
* No UAF, OOB access, repeated release, attacker-controlled corruption, authorization bypass, disclosure, or cross-ownership write is shown.
* No extra availability point: filesystem shutdown is already counted.
* NEW52/B5-R does not apply because there is no heap OOB write or retry-accumulated index.
* NEW53/B3-PENDING and NEW54/B4-PENDING do not apply.

3. Reachability analysis

The trigger is local XFS online repair plus a precisely timed memory-allocation failure. Supplied evidence supports administrative authority for the complete operation, but does not establish that numeric host UID 0 specifically is mandatory. No namespace-scoped or ordinary unprivileged path, special hardware dependency, or network reachability is shown.

4. Primitive and severity reading

The exact defect is untracked allocated filesystem blocks after reservation-object allocation failure, with possible repair termination or filesystem shutdown. This is CLASS_C resource-retention/error-state behavior, not memory corruption or an authorization primitive. Stronger consequences such as arbitrary metadata modification, protected-file corruption, or persistent host-wide exhaustion are unsupported. Auto-downgrade is allowed because no unresolved Important-grade primitive remains.

5. One-sentence report phrase

An administratively invoked XFS online repair can leak staged-btree blocks and shut down the filesystem if a small reservation-record allocation fails.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch and commit identify a constrained administrative allocation-failure cleanup defect without a material corruption or boundary-bypass primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: xfs: don't let memory failures leak blocks and kill repairs [ Upstream
Commit: 3380151cf0ce8ad0c1d356fed51e4b69e1d28e50
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3380151cf0ce8ad0c1d356fed51e4b69e1d28e50

Changed files:
  fs/xfs/scrub/newbt.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=3380151cf0ce8ad0c1d356fed51e4b69e1d28e50

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

The original Linux kernel CVE announcement for CVE-2026-98445 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98445

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:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H
  The Best / paranoid CVSS score: 4.7

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: 0

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).