[CVE-2026-98448][LOW] xfs: release orphanage dir inode if chown fails

[CVE-2026-98448][LOW] xfs: release orphanage dir inode if chown fails

[AL-KERNEL]

CVE: CVE-2026-98448
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: xfs: release orphanage dir inode if chown fails
Commit: 6b66b1a59df6c3f9b4ad9b39a32ca86170ade357
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6b66b1a59df6c3f9b4ad9b39a32ca86170ade357
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98448
Analysis date: Mon, 19 Oct 2026 03:55:42 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A host administrator can leak an XFS orphanage inode reference if online repair reaches a chown failure, but the patch establishes no UAF, memory corruption, authorization bypass, or reliable host-wide denial of service.

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

The original Linux kernel CVE announcement for CVE-2026-98448 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98448

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.

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

CVE-2026-98448	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98448 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=0 LEGACY=LOW RESULT=SAME (final reconciliation agrees; DECISION: both LOW)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';*CWE-772;CWE-404;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '2.3';DESCR 'A reference leak occurs in XFS online repair because xrep_orphanage_create can retain an igrab reference to the orphanage directory inode when xrep_chown_orphanage fails. The demonstrated primitive is persistent inode reference retention, with no supported UAF, out of bounds access, arbitrary write, or information disclosure. For the CVSS the PR:H because reaching the affected XFS repair path normally requires administrative capability to request online filesystem repair. The issue is local and is not network reachable. The base case has AC:H because a chown failure must occur after the inode reference is acquired. Impact is limited availability degradation from a pinned inode or accumulated references, and reliable host wide resource exhaustion is not established. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 2.3 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. No severity changing production threshold or specialist override was recorded. 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. The independent weaker Aegis shadow evaluated CVSS 2.3 and ActionableScore 0 with primitive class CLASS_C and manual review NO. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	DISK SIMPLEFIX LEAK LINUS 	-	-	checked

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

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

1. ActionableScore

* Raw conservative score: 0.
* Conservative score: 0.
* Raw paranoid score: 0.
* Paranoid score: 0.
* No floor or cap was applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Concrete persistent kernel resource or reference leak. An `igrab` reference to `orphanage_inode` is lost when `xrep_chown_orphanage()` fails.
* +1 Important filesystem path. The defect occurs in XFS online metadata repair, although no persistent filesystem corruption is established.
* -2 Proven host-admin-equivalent requirement. Reaching XFS online repair requires host `CAP_SYS_ADMIN`.
* No UAF exists. The inode remains over-referenced rather than being freed while still in use.
* No repeated release exists. The defect is a missing `xchk_irele()`, not a second release through a dangling reference.
* No reliable crash or host-wide resource exhaustion is demonstrated.
* No additional resource-exhaustion point was awarded. Repeated accumulation and substantial availability impact are not established.
* No confidentiality, integrity, authorization-bypass, OOB-write, shared-backing, B5-R, or active-state corruption signal applies.

3. Reachability analysis

The leaking branch is reached during privileged XFS online repair when creation or discovery of the orphanage inode succeeds but `xrep_chown_orphanage()` fails. The complete operation requires host `CAP_SYS_ADMIN`, but it does not inherently require numeric host UID 0 because a process can hold that capability independently.

The operation is not available through an attacker-created user or network namespace, is not network reachable, and has no special hardware requirement. There is no race. A retry might acquire and leak another reference if the same failure remains reproducible, but attacker control over that failure and meaningful accumulation are not established.

4. Primitive and severity interpretation

The exact primitive is retention of an extra reference to an existing XFS orphanage directory inode. The old error path released the dentry but omitted the corresponding inode reference release. The fix routes the failure through `xchk_irele()` and clears the local pointer after ownership is transferred to `sc->orphanage`.

This is neither an ordinary stale cleanup dereference nor a second lifetime mutation through a dangling object. The inode lifetime is extended, not prematurely terminated. Consequently, `PrimitiveClass=NONE` and `RealUAF=NO`.

The demonstrated consequence is a pinned inode reference. Potential accumulation or unmount interference is unresolved, while memory exhaustion, kernel panic, filesystem corruption, privilege escalation, and protected-resource modification are not demonstrated. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` because no unresolved corruption or security-boundary primitive remains.

5. One-sentence report phrase

A host administrator can leak an XFS orphanage inode reference if online repair reaches a chown failure, but the patch establishes no UAF, memory corruption, authorization bypass, or reliable host-wide denial of service.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The issue is a host-administrator-only reference leak with no demonstrated accumulation, crash, memory corruption, authorization bypass, or cross-boundary impact.

7. Call-site confidence

Call-site confidence: high

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

Patch: xfs: release orphanage dir inode if chown fails
Commit: 6b66b1a59df6c3f9b4ad9b39a32ca86170ade357
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6b66b1a59df6c3f9b4ad9b39a32ca86170ade357

Commit description:

LOLLM points out that we leak the igrab'd reference to the orphanage
directory inode if chowning it fails.  Fix that.

Cc: stable@vger.kernel.org # v6.10
Fixes: 1e58a8c ("xfs: move orphan files to the orphanage")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Assisted-by: LOLLM # finding obvious bugs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  fs/xfs/scrub/orphanage.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=6b66b1a59df6c3f9b4ad9b39a32ca86170ade357

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

The original Linux kernel CVE announcement for CVE-2026-98448 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98448

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:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 2.3

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).