[CVE-2026-98635][IMPORTANT] scsi: block: Fix zones_cond out-of-bounds write on zone report [ Upstream

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

CVE: CVE-2026-98635
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: scsi: block: Fix zones_cond out-of-bounds write on zone report [ Upstream
Commit: ca688bb207957cffa5a8cad207329b0dcac1f2c0
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ca688bb207957cffa5a8cad207329b0dcac1f2c0
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98635
Analysis date: Sat, 24 Oct 2026 06:50:46 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
A malicious zoned device can drive repeated constrained one-byte writes beyond an undersized zone-condition heap array, creating a concrete kernel heap-corruption primitive with unknown adjacent-object impact.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-98635 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98635

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: IMPORTANT
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-2026-98635	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2026-98635 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=IMPORTANT RESULT=DIFF INDEPENDENT_LEGACY=IMPORTANT INDEPENDENT_RESULT=DIFF TEMP_KPANIC_MERGE=IMPORTANT_WINS_DISAGREEMENT PRE_MERGE_LEGACY=IMPORTANT (final Legacy and Aegis differ; FINAL: IMPORTANT, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-190;CWE-681;*CWE-20;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '8.8';DESCR 'The zones_cond array is allocated from the capacity derived zone count, but its write index comes from the device supplied report_zones walk and was not checked against the allocation size. A malicious or faulty zoned block device can report additional zones and cause repeated one byte writes beyond the heap allocation. A zone count above UINT_MAX also truncates when stored in the unsigned int nr_zones field, which can severely undersize the array while report processing continues. For the CVSS the PR:N value is used because an attacker controlling the attached or virtual storage device does not need an authenticated user context on the vulnerable host. The attack vector is adjacent because control of a zoned storage device or storage backend is required and ordinary network traffic is not sufficient. The concrete primitive is an out of bounds write of constrained zone condition values. Impact is at least host denial of service through kernel memory corruption and may permit confidentiality or integrity impact if adjacent heap objects can be modified in an exploitable way. Automated impact decision path. The original SimpleNet classifier selected IMPORTANT. The primary LLM estimated paranoid CVSS 8.8 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 KP and FD specialist checks stage IMPORTANT to IMPORTANT because a specific evidence based protection or manual review veto was applied. final reconciliation stage IMPORTANT to IMPORTANT because KP specialist did not establish a qualifying panic. 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 produced a review artifact and its decision was processed by the applicable downgrade and preservation rules. Exact triggered rule markers were V59_LEGACY_CLASSA_KP_VETO and MANUAL_REVIEW_REQUIRED and V42_LEGACY_CLASSA_FD_VETO and MANUAL_REVIEW_REQUIRED and TEMP_KPANIC_MERGE_IMPORTANT_WINS and KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 4.3 and ActionableScore 2 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 IMPORTANT.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)	MAYBE	WRITE OOB SIMPLEFIX HARDWARE LINUS V59_LEGACY_CLASSA_KP_VETO MANUAL_REVIEW_REQUIRED V42_LEGACY_CLASSA_FD_VETO MANUAL_REVIEW_REQUIRED TEMP_KPANIC_MERGE_IMPORTANT_WINS KPANIC_UNSUPPORTED_REMOVED	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
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 downstream effects are not sufficiently evidenced.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +2 — Confirmed attacker-influenced heap OOB write: `blk_zone_set_cond()` writes a one-byte device-reported condition through an unchecked report index beyond the allocated `zones_cond` array.
* +1 — Material corrupt leverage: the device controls the reported zone sequence, overwrite count, and constrained condition values, allowing repeated sequential corruption rather than a single fixed accidental write.
* +1 — Firmware/device-mediated external influence: a malicious zoned device or virtual storage backend can supply inconsistent zone reports.
* +1 — Reliable kernel crash/strong DoS is plausible from repeated heap corruption.
* No extra availability point: it would duplicate the same prospective crash.
* No C/I points: no adjacent victim, disclosure, protected-state modification, arbitrary target, or LPE is shown.
* No arbitrary-write or controlled-reclaim bonus.
* B5-R is not established: the index advances during one report walk, not across retries due to a missing reset, and no specific corrupted adjacent object is shown being consumed later.

3. Reachability analysis

The grounded attacker is a malicious or faulty zoned storage device/backend, not an ordinary network peer. The supplied evidence states that this actor needs no authenticated host user or host-administrator power once the device is exposed, so `HostAdminRequired=NO` and `RequiresHostUID0=NO`. Attachment or virtual-device provisioning may require prior host configuration, but the exact provisioning model is not supplied. No user/net-namespace capability path is established. No timing race is required; sufficiently many reported zones deterministically advance the write beyond the allocation.

4. Primitive and severity reading

This is a confirmed, repeated heap OOB write into storage following `zones_cond`, caused both by unchecked device-driven report indices and possible 64-to-32-bit zone-count truncation. It is not a UAF or stale-storage case. The write values are constrained zone-condition bytes and the target progresses sequentially, but the affected adjacent heap object is unknown.

The primitive is CLASS_A because attacker-influenced heap writes beyond the allocation are directly shown. Crash is plausible; arbitrary kernel write, sensitive-object corruption, confidentiality loss, and privilege escalation remain unproven. Important review is required because the concrete heap-corruption primitive must not be downgraded solely for lacking a completed exploit.

5. One-sentence report phrase

A malicious zoned device can drive repeated constrained one-byte writes beyond an undersized zone-condition heap array, creating a concrete kernel heap-corruption primitive with unknown adjacent-object impact.

6. Manual review advice

MANUAL CHECK REQUIRED

Determine reachable device/backend models, allocator adjacency, and whether overwritten objects are subsequently consumed before fault detection.

7. Call-site confidence

Call-site confidence: medium

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

Patch: scsi: block: Fix zones_cond out-of-bounds write on zone report [ Upstream
Commit: ca688bb207957cffa5a8cad207329b0dcac1f2c0
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ca688bb207957cffa5a8cad207329b0dcac1f2c0

Changed files:
  block/blk-zoned.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=ca688bb207957cffa5a8cad207329b0dcac1f2c0

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

The original Linux kernel CVE announcement for CVE-2026-98635 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98635

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:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 8.8

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

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).