From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99015][MODERATE 7.0] Bluetooth: hci_sock: Serialize dead-device detachment Date: Tue, 27 Oct 2026 00:53:00 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99015 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 4 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 37cef0c8fb537f40600910d2c2e5f2d5509305f3 List-Id: CVE: CVE-2026-99015 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: Bluetooth: hci_sock: Serialize dead-device detachment Commit: 37cef0c8fb537f40600910d2c2e5f2d5509305f3 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=37cef0c8fb537f40600910d2c2e5f2d5509305f3 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99015 Analysis date: Tue, 27 Oct 2026 00:53:00 -0400 ActionableScore: 4 ActionableScore lower bound: unknown Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: Concurrent HCI socket rebinding and controller detachment can leave monitor replay using a freed `hci_dev`, causing a NULL dereference or crash-capable UAF. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99015 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99015 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-2026-99015 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-99015 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=6 LEGACY=MODERATE_KPANIC RESULT=SAME (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-362;*CWE-416;**CWE-476;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A race in hci_sock_bind can detach an HCI socket and drop the final device reference while monitor replay or socket delivery still uses the old hdev pointer. The demonstrated primitives are a NULL pointer dereference and a retained pointer use after free when create_monitor_ctrl_open reads hdev id, with kernel crash as the immediate impact. For the CVSS the PR:L value reflects that triggering requires a local process with access to the Bluetooth HCI socket interface, while capability checks and control over device unregister may vary by socket channel and deployment. AC:H reflects the required race with controller unregister and concurrent replay or delivery. Impact is at least a local denial of service and in the worst defensible case may include confidentiality or integrity impact if the freed hci_dev object is reused, so the UAF requires manual review. The issue is not directly network reachable through ordinary Bluetooth traffic. 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 Borderline / manual review recommended. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage IMPORTANT to MODERATE_KPANIC because the CVSS score, vector or bug class threshold 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 LOWERED_FROM_HIGH_BASED_ON_NULLPTR. The independent weaker Aegis shadow evaluated CVSS 2.4 and ActionableScore 6 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4) MAYBE REMOTE DANGER NULLPTR RACE UAF NETWORK KERNEL_PANIC_PLUS_UAF HARDWARE LINUS KPANIC KPANIC LOWERED_FROM_HIGH_BASED_ON_NULLPTR - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 PrimitiveClass=CLASS_B RealUAF=YES HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 2. * Conservative score: 4. Real-UAF floor 4 applied: 2 -> 4. * Raw paranoid score: 2. * Paranoid score: 4. No additional exploit primitive supports a paranoid increment; Real-UAF floor 4 applied. * Final recommended bucket: **Borderline / manual review recommended**:: 2. Signal breakdown * +2 — Real active-object UAF: replay can retain `hdev` while bind clears the socket pointer and drops the final device reference. * +1 — Plausible kernel crash: KASAN reports the corresponding NULL dereference; retained-pointer execution can instead dereference freed `hci_dev`. * -1 — Hard race: exploitation requires controller unregistration, rebinding, and concurrent replay or delivery within the detach window. * No controlled reclaim, attacker-shaped replacement object, post-free write, callback consumption, repeated refcount mutation, arbitrary access, or disclosure is shown. * No extra availability point: it would duplicate the same crash. * The stale use reads `hdev->id`; object complexity alone does not establish structured stale-object leverage. * The separate stale-binding delivery behavior can queue a frame after detach/rebind, but no protected recipient, namespace boundary, or security-policy bypass is established. 3. Reachability analysis A local process can invoke socket bind, but the evidence does not establish who can perform the complete sequence, especially controller unregistration and monitor-control replay. The relevant HCI channel capability checks, capability namespace, and whether a non-host-admin actor controls all stages are absent. Thus host-admin and namespace-scoped privilege remain unknown. Ordinary Bluetooth traffic is not a direct remote trigger. The race appears timing-sensitive and may depend on device teardown or privileged control activity. 4. Primitive and severity reading The primitive is an active structured `hci_dev` lifetime violation, not fixed stale storage: a reader can retain the old pointer beyond the final `hci_dev_put()` and then read `hdev->id`. This is CLASS_B. The demonstrated effect is NULL/UAF dereference and kernel crash; useful post-reclaim behavior is unproven. There is no second lifetime/refcount mutation. ImportantCandidate is NO because the supplied evidence supports a constrained crash-oriented stale read without material reuse or boundary leverage. Auto-downgrade remains allowed, though manual review is advisable due to the genuine UAF. 5. One-sentence report phrase Concurrent HCI socket rebinding and controller detachment can leave monitor replay using a freed `hci_dev`, causing a NULL dereference or crash-capable UAF. 6. Manual review advice MANUAL CHECK RECOMMENDED Confirm HCI channel permissions, control over controller unregistration, and whether stale frame delivery crosses any socket or namespace trust boundary. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: Bluetooth: hci_sock: Serialize dead-device detachment Commit: 37cef0c8fb537f40600910d2c2e5f2d5509305f3 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=37cef0c8fb537f40600910d2c2e5f2d5509305f3 Commit description: Rebinding an HCI socket after its controller is unregistered can race monitor control replay and crash the kernel. hci_sock_bind() clears hci_pi(sk)->hdev and drops the device reference under only the socket lock, whereas send_monitor_control_replay() holds hci_sk_list.lock for reading. Replay can observe a non-NULL hdev, then bind can clear it and drop the last reference before create_monitor_ctrl_open() reads hdev->id. This can cause a NULL pointer dereference if the pointer is reloaded, or a use-after-free if the old pointer is retained. The kernel reported: KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f] RIP: 0010:create_monitor_ctrl_open+0x579/0x800 Call Trace: hci_sock_bind+0xd96/0x1190 __sys_bind+0x166/0x200 __x64_sys_bind+0x6d/0xb0 do_syscall_64+0xdd/0x4a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f The same missing serialization lets hci_send_to_sock() select a socket for the old device and queue its frame after bind has detached the socket or installed a new binding. Take hci_sk_list.lock for writing when clearing the device pointer and resetting the socket state. This waits for existing replay and delivery readers to finish before detachment and prevents later readers from using the old binding. Keep hci_dev_put() outside the critical section because the final device release can sleep. Fixes: e044809 ("Bluetooth: defer cleanup of resources in hci_unregister_dev()") Cc: stable@vger.kernel.org Assisted-by: GPT-6 Astra Signed-off-by: Chengfeng Ye Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman Changed files: net/bluetooth/hci_sock.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=37cef0c8fb537f40600910d2c2e5f2d5509305f3 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99015 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99015 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: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 alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).