* [CVE-2026-98545][MODERATE 7.0] ata: libata-scsi: bound the ATA passthru sense descriptor writes
@ 2026-10-24 9:49 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-24 9:49 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98545
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: ata: libata-scsi: bound the ATA passthru sense descriptor writes
Commit: c698f6deabf680f8f4a1727ef2dc80fe78815fbf
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c698f6deabf680f8f4a1727ef2dc80fe78815fbf
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98545
Analysis date: Sat, 24 Oct 2026 05:49:20 -0400
ActionableScore: 4
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES
Summary:
A malicious ATAPI sense response can drive a confirmed 14-byte heap OOB descriptor write and crash-capable kernel corruption, with stronger adjacent-object effects unresolved.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98545 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98545
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-98545 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98545 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | 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:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-125;*CWE-20;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A faulty or malicious ATAPI device can control the additional sense length in sb 7 after a failed ATA PASS-THROUGH command. The kernel can then walk beyond the 96 byte sense buffer or write a 14 byte ATA Status Return descriptor beyond its end. KASAN reproduced both slab out of bounds read and slab out of bounds write primitives. The direct impact is a kernel crash and denial of service. Kernel heap corruption also creates a plausible but unproven path to confidentiality loss integrity impact or privilege escalation. For the CVSS the PR:L value in the paranoid vector assumes a local user has delegated access to issue ATA pass through commands to an attacker controlled or emulated ATAPI device. Physical malicious device exposure lacks victim system privileges but requires attachment and a command path that reaches the failing REQUEST SENSE response. Automated impact decision path. The original SimpleNet classifier selected IMPORTANT. The primary LLM estimated paranoid CVSS 7 and the production ActionableScore returned 4 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were ActionableScore thresholds stage IMPORTANT to MODERATE_KPANIC because the ActionableScore threshold rule was applied. KP and FD specialist checks stage MODERATE_KPANIC to MODERATE because KP specialist did not establish a qualifying panic. final reconciliation stage MODERATE to MODERATE_KPANIC because the cross model evidence reconciliation 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 DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN5 and DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 1.8 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 Actionable Moderate / Strong Important candidate requiring manual review (with actual score 4) MAYBE WRITE KASAN OOB HARDWARE LINUS DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN5 DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP KPANIC V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=4
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw base score: 4.
* Conservative score: 4; no floor or cap applied.
* Raw paranoid score: 4.
* Paranoid score: 4; delegated local passthrough access is not sufficiently proven for another reachability point.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
* +2 — Strong corruption primitive: attacker-influenced `sb[7]` and descriptor layout can place a confirmed 14-byte write past the 96-byte slab buffer.
* +1 — Reliable kernel crash/strong DoS: KASAN reproduced slab OOB faults in both descriptor walking and command completion.
* +1 — Device-mediated external influence: a faulty or malicious ATAPI device supplies the malformed REQUEST SENSE response.
* No physical-only penalty: physical attachment is one path, but emulated or delegated passthrough paths are also described and exclusivity is not proven.
* No additional point for the OOB read, allocation invariant, or availability; these overlap the corruption/crash already scored.
* Arbitrary target, arbitrary payload, named adjacent victim, disclosure, controlled reclaim, and LPE are not shown.
* NEW52 B5-R does not apply: there is no retry-accumulated index or retry sequence.
* B3-PENDING and B4-PENDING do not apply: no shared backing or authorization decision is involved.
3. Reachability analysis
The malformed bytes are controlled by an ATAPI device, but the complete attacker path is unresolved. A malicious physical device is credible, and QEMU demonstrates emulated-device feasibility, while ordinary local access to ATA PASS-THROUGH is not established. The hint’s delegated `PR:L` scenario is explicitly an assumption rather than proof. Consequently, host-admin, UID 0, namespace capability, and prior setup requirements remain unknown. No race is required.
4. Primitive and severity reading
This is a bounded but genuine heap/slab OOB write, not a UAF or stale-storage case. The patch corrects both the descriptor-search bound and the required `len + 22` capacity, and separately rejects an existing descriptor too near the buffer end. The shown effects are OOB access and crash-capable heap corruption. Exploitation through an adjacent object is unproven, but the confirmed attacker-influenced write is CLASS_A and must not be auto-downgraded merely because its target and ultimate non-crash consequences remain unidentified.
5. One-sentence report phrase
A malicious ATAPI sense response can drive a confirmed 14-byte heap OOB descriptor write and crash-capable kernel corruption, with stronger adjacent-object effects unresolved.
6. Manual review advice
MANUAL CHECK REQUIRED
Confirm passthrough exposure and adjacent slab layout; the real OOB write preserves an Important candidate despite uncertain privilege and exploitation impact.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: ata: libata-scsi: bound the ATA passthru sense descriptor writes
Commit: c698f6deabf680f8f4a1727ef2dc80fe78815fbf
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c698f6deabf680f8f4a1727ef2dc80fe78815fbf
Commit description:
When an ATA PASS-THROUGH command to an ATAPI device fails, the sense
buffer holds the device's REQUEST SENSE reply, and
ata_scsi_set_passthru_sense_fields() trusts its additional length
byte, sb[7], when adding the ATA Status Return descriptor. A faulty
or malicious device can use that to make the kernel read and write
past the 96-byte buffer in three ways:
- scsi_sense_desc_find() is passed sb[7] + 8 as the buffer length, so
its clamp against sb[7] does nothing and the walk runs off the end.
- A type-9 descriptor found near the end is filled in unchecked.
- A new descriptor at sb[8 + len] needs len + 22 bytes, not len + 14,
so len 75..82 writes up to 8 bytes past the end.
Reproduced with KASAN under qemu, with the emulated ATAPI REQUEST SENSE
reply patched:
BUG: KASAN: slab-out-of-bounds in scsi_sense_desc_find+0x1a5/0x210
BUG: KASAN: slab-out-of-bounds in ata_scsi_qc_complete+0x1a15/0x1a50
Both are gone with this patch, and a valid descriptor is still filled
in.
Fixes: 9798192 ("ata: libata-scsi: Do not overwrite valid sense data when CK_COND=1")
Cc: [email protected]
Reviewed-by: Damien Le Moal <[email protected]>
Signed-off-by: Matthias Goergens <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Niklas Cassel <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
drivers/ata/libata-scsi.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=c698f6deabf680f8f4a1727ef2dc80fe78815fbf
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98545 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98545
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:P/AC:L/PR:N/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: 4
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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