* [CVE-2026-98738][MODERATE 7.0] Bluetooth: Serialize SMP remote OOB data access [ Upstream
@ 2026-10-19 9:37 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-19 9:37 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98738
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: Bluetooth: Serialize SMP remote OOB data access [ Upstream
Commit: 1e11412a1b9854a89d044576d616675b16141d87
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1e11412a1b9854a89d044576d616675b16141d87
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98738
Analysis date: Mon, 19 Oct 2026 05:37:07 -0400
ActionableScore: 4
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES
Summary:
A race between Bluetooth SMP pairing processing and remote OOB data removal causes a confirmed active-object slab use-after-free with realistic kernel denial of service and unresolved pairing-state consequences.
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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-98738 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98738
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-2026-98738 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98738 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=4 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:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;CWE-367;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.5';DESCR 'A race in Bluetooth SMP remote OOB handling allows build_pairing_cmd to retain and read an oob_data entry after a concurrent management command removes and frees it. KASAN confirms a slab use-after-free while the receive path reads the present flag or copies remote random and confirmation values. A Bluetooth peer within radio range can exercise the SMP receive path, but reliable triggering also depends on a concurrent remote OOB removal or update and therefore has high attack complexity. For the CVSS the PR:N value is used for the paranoid adjacent attack scenario because the peer does not need an account or privileges on the target when a legitimate local Bluetooth service performs the concurrent removal. Impact is at least denial of service through a kernel crash and may include confidentiality or integrity impact if reclaimed slab contents are consumed as pairing data. Privilege escalation is not demonstrated, but the confirmed use-after-free and cross-context trigger require manual review. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 7.5 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 CVSS and initial triage stage MODERATE_KPANIC to MODERATE_KPANIC because the CVSS score, vector or bug class 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 INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS and DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 4.7 and ActionableScore 4 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 REMOTE OOB LOCK DANGER INIT UAF NETWORK HARDWARE LINUS INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP KPANIC V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED - - checked
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ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=4
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw conservative score: 3
* Conservative score: 4
* Raw paranoid score: 3
* Paranoid score: 4
* Applied conservative floor: 3 -> 4 under REAL UAF FLOOR 4.
* Applied paranoid floor: 3 -> 4 under REAL UAF FLOOR 4.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
* +2 Real UAF. A remote OOB list entry can be freed while `build_pairing_cmd()` still traverses or dereferences it. KASAN directly confirms slab use-after-free.
* +1 realistic kernel crash. Traversal or field access through reclaimed slab storage can produce an Oops or kernel crash.
* +0 structured stale-object leverage. The stale object is active structured state and its `present`, random, confirmation, and list fields are consumed. However, attacker-controlled reclaim or replacement contents are not established.
* +0 confidentiality. No path copying reclaimed bytes to userspace or a remote peer is demonstrated.
* +0 integrity. Stale values enter pairing processing, but an authentication bypass or unauthorized successful pairing is not established.
* +0 remote-reachability bonus. A Bluetooth peer can reach the SMP reader, but the complete race also needs a concurrent local management add, remove, update, or clear operation.
* No race penalty. The required interleaving is established, but the evidence does not show that it is a genuinely one-shot or materially uncontrollable race.
* No privilege penalty. Access restrictions for the complete two-sided trigger are unresolved. The local management writer may be privileged, while the SMP reader is radio-adjacent.
* No concrete repeated release or refcount operation exists. The stale path reads or traverses the freed object rather than releasing it again.
* Controlled reclaim, arbitrary write, callback control, disclosure, authorization bypass, and privilege escalation are not demonstrated.
* NEW52 B5-R does not apply because there is no retry-accumulated heap OOB write.
* NEW53 B3-PENDING does not apply because there is no demonstrated shared-backing write.
* NEW54 B4-PENDING does not apply because no authorization DENY-to-ALLOW transition exists.
* V33 does not independently apply because attacker-influenced corruption by a write is not established. This is an active-state stale read and traversal UAF.
3. Reachability analysis
A Bluetooth peer within radio range can drive the SMP receive path that calls `build_pairing_cmd()`. The conflicting writer is a local Bluetooth management operation that adds, updates, removes, or clears remote OOB data through the HCI management socket.
The supplied evidence does not establish that an ordinary remote peer can independently force the management-side removal. It also does not fully establish whether one below-host-admin local principal can perform the complete reader and writer sequence. Consequently, `HostAdminRequired` and `NamespaceScopedPrivilege` remain `UNKNOWN`.
No Internet-routable trigger is established. Bluetooth proximity and an enabled Bluetooth controller are prerequisites. No unusual hardware beyond a Bluetooth-capable system is required. Repeated management updates could create additional race opportunities, but attacker control of both sides is unresolved.
4. Primitive and severity interpretation
The exact primitive is a slab use-after-free read and list traversal involving an active `oob_data` object. A writer unlinks and frees the entry while the SMP receive path can still traverse the list, read `present`, or copy random and confirmation values.
This is not fixed stale storage and not a cleanup-only dereference. It occurs during active Bluetooth pairing processing. It is therefore `CLASS_B`, but not `CLASS_A`, because no controlled reclaim, attacker-shaped replacement object, directed write, callback influence, or authorization bypass is established.
The demonstrated consequence is KASAN-detected UAF with realistic kernel DoS. Incorrect pairing behavior is also plausible. Disclosure, authentication bypass, privilege escalation, and useful post-reclaim control remain speculative.
`ImportantCandidate=YES` because the UAF affects active receive-path state, can occur during list traversal, and consumes structured pairing data after its lifetime may have ended. `AutoDowngradeAllowed=NO` because automatically treating it as an ordinary crash-only defect would discard unresolved active-object and pairing-state implications. This classification preserves manual review without asserting proven Important severity.
5. One-sentence report phrase
A race between Bluetooth SMP pairing processing and remote OOB data removal causes a confirmed active-object slab use-after-free with realistic kernel denial of service and unresolved pairing-state consequences.
6. Manual review recommendation
MANUAL CHECK REQUIRED
The UAF is confirmed in active Bluetooth receive processing, while complete attacker privilege, reclaim behavior, and security consequences of stale OOB pairing data remain unresolved.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: Bluetooth: Serialize SMP remote OOB data access [ Upstream
Commit: 1e11412a1b9854a89d044576d616675b16141d87
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1e11412a1b9854a89d044576d616675b16141d87
Changed files:
include/net/bluetooth/hci_core.h
net/bluetooth/hci_core.c
net/bluetooth/smp.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=1e11412a1b9854a89d044576d616675b16141d87
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98738 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98738
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:L/I:L/A:H
The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
The Best / paranoid CVSS score: 7.5
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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