* [CVE-2026-90087][MODERATE REGULAR] Bluetooth: do not leak an hci_conn when a second LE connect is rejected [ Upstream
@ 2026-09-17 22:46 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-17 22:46 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-90087
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Bluetooth: do not leak an hci_conn when a second LE connect is rejected [ Upstream
Commit: 2eafcf310f4e0ad4f387881db01116bbe3cc0b39
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2eafcf310f4e0ad4f387881db01116bbe3cc0b39
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90087
Analysis date: Thu, 17 Sep 2026 18:46:01 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
Bluetooth LE connection handling can leak an `hci_conn` when a rejected second pending LE connection is matched against the wrong pending connection, leaving outgoing LE connects blocked with `EBUSY` until adapter reset.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90087 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90087
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 REGULAR
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-2026-90087 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-90087 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-772;CWE-404;CWE-703;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'Bluetooth LE connection handling can leak an hci_conn object when a second pending LE connection is rejected and create_le_conn_complete checks the first pending connection instead of the connection that actually failed. The leaked connection remains in BT_CONNECT and blocks later outgoing LE connection attempts with EBUSY until the adapter is reset, causing a persistent Bluetooth LE denial of service. For the CVSS the PR:N is used for the paranoid adjacent attack case because a nearby attacker may only need Bluetooth radio reachability if the victim automatically initiates LE connections to attacker controlled peers. The issue is adjacent network reachable over Bluetooth rather than reachable over the public Internet. Impact is denial of service for Bluetooth LE connectivity only, with no evidence of memory corruption, information disclosure, or privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) YES REMOTE LEAK NETWORK HARDWARE DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH YES NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
## 1. ActionableScore
* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 3
* Paranoid score: 3
* Final recommended bucket: **Borderline / manual review recommended**::
No floor or cap changed the score.
## 2. Signal breakdown
Conservative positive signals:
* +1 Concrete persistent kernel resource/reference leak. The failed `hci_conn` is not failed/released and remains stuck in `BT_CONNECT`.
* +1 Persistent device/service availability impact. Outgoing LE connections are blocked with `EBUSY` until adapter reset.
Paranoid additional signal:
* +1 Firmware/wireless adjacent influence. A nearby BLE peer scenario may contribute to the two-pending-connect condition and controller rejection, but this is mediated by Bluetooth controller behavior and victim connection policy.
Non-awarded signals:
* RealUAF not awarded. The patch establishes a leaked `hci_conn`, not post-free use.
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Confidentiality and integrity not awarded.
* Host-wide kernel crash not demonstrated.
* Direct Internet/network reachability not awarded. Bluetooth adjacent reachability is not equivalent to AV:N.
* Race penalty not applied. The issue involves ordering of pending connections, but the evidence does not establish a narrow one-shot uncontrollable timing race.
* ImportantCandidate not set. This is persistent Bluetooth LE DoS, not unresolved kernel memory corruption or security-boundary bypass.
## 3. Reachability analysis
The direct local trigger is a process or Bluetooth management stack initiating multiple LE connection attempts such that two LE connections are pending at once. The exact required local privilege depends on how Bluetooth management is exposed on the evaluated system, for example BlueZ policy, HCI socket access, or service-mediated connection requests. The supplied evidence does not prove host-admin-equivalent privilege, but also does not prove a fully ordinary unprivileged local trigger.
A paranoid adjacent scenario is plausible if a nearby attacker controls BLE peers and the victim system automatically attempts LE connections to them on the same interval. That does not prove direct unauthenticated remote reachability because the victim must initiate or be configured to initiate the affected connections.
No namespace-scoped privilege path is indicated. No special rare hardware penalty is applied, although the observed behavior mentions `bcm43438`.
## 4. Primitive and severity interpretation
The primitive is a persistent `hci_conn` lifetime/resource leak caused by checking whether any LE connection is pending instead of checking whether the specific failed connection is still pending. The leaked object remains in `BT_CONNECT`, causing later `hci_connect_le()` attempts to fail with `EBUSY`.
This is not an active post-free object use and not a concrete repeated release/refcount mutation. It is best classified as CLASS_C because the demonstrated behavior is invalid state and persistent Bluetooth LE denial of service without an independently useful corruption primitive.
Demonstrated consequence: outgoing Bluetooth LE connections do not recover until adapter reset.
Speculative consequence: broader Bluetooth availability disruption if the adapter is relied upon for service connectivity.
Leverage beyond DoS is not established. Therefore `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES`.
## 5. One-sentence report phrase
Bluetooth LE connection handling can leak an `hci_conn` when a rejected second pending LE connection is matched against the wrong pending connection, leaving outgoing LE connects blocked with `EBUSY` until adapter reset.
## 6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Reason: the issue is not memory corruption and is likely DoS-only, but the possible adjacent Bluetooth trigger model and persistent adapter-level impact should be verified against product exposure and Bluetooth auto-connect policy.
## 7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: Bluetooth: do not leak an hci_conn when a second LE connect is rejected [ Upstream
Commit: 2eafcf310f4e0ad4f387881db01116bbe3cc0b39
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2eafcf310f4e0ad4f387881db01116bbe3cc0b39
Changed files:
net/bluetooth/hci_sync.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=2eafcf310f4e0ad4f387881db01116bbe3cc0b39
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90087 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90087
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:L/UI:N/S:U/C:N/I:N/A:L
The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 5.3
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: 2
Paranoid ActionableScore: 3
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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR
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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