From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-93247][MODERATE REGULAR] Bluetooth: mgmt: fix 'hdev->discovery.uuids' NULL dereference [ Upstream Date: Thu, 24 Sep 2026 18:17:10 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-93247 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 2 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: f02c01ccd12cb2b8a290077d4c90f29a6e109b16 List-Id: CVE: CVE-2026-93247 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: Bluetooth: mgmt: fix 'hdev->discovery.uuids' NULL dereference [ Upstream Commit: f02c01ccd12cb2b8a290077d4c90f29a6e109b16 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f02c01ccd12cb2b8a290077d4c90f29a6e109b16 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93247 Analysis date: Thu, 24 Sep 2026 18:17:10 -0400 ActionableScore: 2 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93247 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93247 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-93247 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-93247 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-362;**CWE-476;CWE-667;BEST CVSS score: '4.8';DESCR 'A race in Bluetooth discovery UUID filter handling can create an inconsistent state where uuid_count is nonzero while the uuids pointer is NULL. A Bluetooth device within radio range can supply advertising reports that reach eir_has_uuids while a local management operation starts or clears service discovery, causing a NULL pointer dereference and kernel crash. For the CVSS the PR:L because reliable triggering requires a local process with Bluetooth management privileges, typically CAP_NET_ADMIN, to configure the discovery UUID filter. The external Bluetooth device only provides adjacent radio traffic and does not by itself trigger the vulnerable state. The issue is adjacent network reachable through Bluetooth advertising traffic, but the race requires a timing window. Impact is denial of service only. No use after free, out of bounds access, information disclosure, or write primitive is demonstrated by the patch. YES REQUIRES MANUAL CHECK';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) YES REMOTE OOB LOCK DANGER NULLPTR RACE NETWORK HARDWARE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 2 * Conservative score: 2 * Raw paranoid score: 2 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap was applied. Conservative and paranoid scores are identical because the supplied patch establishes a NULL dereference crash path, not a lifetime or memory-corruption primitive. 2. Signal breakdown Positive signals: * +1 Firmware-mediated external influence. Bluetooth advertising reports from a nearby device are delivered through the Bluetooth controller and HCI receive path into `hci_rx_work`, then may reach `eir_has_uuids()`. This is not scored as direct remote reachability because reliable triggering also requires a local discovery-state transition. * +1 Reliable kernel crash / strong DoS. The supplied trace shows a NULL pointer dereference in `eir_has_uuids()` from the Bluetooth receive workqueue. The inconsistent `uuid_count != 0` and `uuids == NULL` state directly supports an Oops and potential kernel DoS. Negative signals: * No privilege penalty applied. The supplied input indicates that a local Bluetooth management operation is needed to configure service discovery, but it does not show the exact command dispatcher and capability check needed to establish whether host-admin-equivalent privilege is required. * No hard-race penalty applied. A race is explicitly shown, but the supplied code does not establish that the timing is rare, one-shot, externally uncontrollable, or materially difficult to repeat. Local discovery operations and nearby advertising traffic can plausibly be repeated. Important non-awarded signals: * No real UAF or stale post-free dereference is established. `uuids` is explicitly set to NULL after `kfree()`, and the vulnerable use is a NULL dereference rather than dereferencing freed storage. * No controlled reclaim, object replacement, arbitrary write, directed write, type confusion, refcount takeover, or callback influence is demonstrated. * No confidentiality or integrity signal is awarded. The patch provides no information disclosure, unauthorized state modification, or attacker-controlled memory write primitive. * No direct remote reachability +2 is awarded. A nearby Bluetooth device can provide advertising data, but it cannot independently create the invalid discovery filter state. A local management operation is also required. * No local unprivileged trigger +1 is awarded. The complete privilege boundary for `start_service_discovery()` is not shown. * No extra Availability point is awarded because the observed Oops and resulting DoS are already counted by the reliable kernel crash signal. * No Important-preserving primitive is established. This is an inconsistent-state NULL dereference, not a UAF, double free, OOB access, or ownership violation. 3. Reachability analysis The demonstrated trigger requires two contributing conditions: 1. A local process initiates or changes Bluetooth service discovery so that `start_service_discovery()` and `hci_discovery_filter_clear()` can race while updating `hdev->discovery.uuid_count` and `hdev->discovery.uuids`. 2. A Bluetooth device within radio range provides an advertising report that is processed by `hci_rx_work` and reaches `mgmt_device_found()`, `is_filter_match()`, and `eir_has_uuids()` during the inconsistent state window. The external attacker role is Bluetooth-adjacent, not Internet-remote. Bluetooth advertising traffic is processed through the local Bluetooth controller and HCI stack. The nearby device supplies traffic that reaches the vulnerable receive path, but does not by itself perform the discovery management operation required to create the invalid state. The supplied patch does not include the management-command dispatch and capability checks for `MGMT_OP_START_SERVICE_DISCOVERY`. Therefore, it is not technically justified to mark HostAdminRequired as YES or NO. The likely requirement is Bluetooth management privilege such as `CAP_NET_ADMIN`, but the exact user-namespace and network-namespace scope of the complete operation is not established here. NamespaceScopedPrivilege is UNKNOWN. The patch does not establish that an attacker can create a namespace, obtain sufficient namespaced capability, access the relevant Bluetooth HCI device, configure discovery, and receive the required advertising reports without host-level Bluetooth administration or prior device exposure. No special hardware beyond an enabled Bluetooth adapter and an advertising-capable nearby Bluetooth device is required. The race may be repeatable through repeated discovery changes and advertising activity, but no evidence demonstrates a reliable unprivileged trigger or controlled timing mechanism. 4. Primitive and severity interpretation The exact primitive is a synchronization failure between the paired discovery fields `uuid_count` and `uuids`. `hci_discovery_filter_clear()` previously wrote `uuid_count = 0` before taking `discovery.lock`, while `start_service_discovery()` separately wrote a nonzero `uuid_count` and installed a newly allocated UUID array without holding that same lock. A subsequent continuation of the clear path could free the new array and set `uuids = NULL`, leaving a nonzero count paired with a NULL pointer. The later active receive path checks `uuid_count` and passes `uuids` into `eir_has_uuids()` without an effective paired-state synchronization guarantee. The resulting dereference is NULL, as confirmed by the supplied call trace. This is not fixed stale storage and not an active structured-object UAF. It is also not a repeated release or refcount mutation case. The `kfree()` call is followed by assignment of NULL, and the demonstrated fault occurs when a later reader consumes the NULL value. There is no evidence that a stale dangling pointer is dereferenced after the free. The primitive is therefore CLASS_C. The demonstrated consequence is a kernel Oops or crash resulting in denial of service. A stronger consequence such as privilege escalation, confidentiality impact, integrity impact, arbitrary kernel read or write, or controlled object reuse is speculative and unsupported by the patch. ImportantCandidate is NO because there is no unresolved Class B lifetime/corruption primitive and no Class A security-boundary primitive. AutoDowngradeAllowed is YES because the established issue is a constrained crash-only invalid-state condition without demonstrated memory corruption or authorization bypass. Operationally, systems with Bluetooth enabled and exposed to nearby devices may experience a local host DoS if a local actor can concurrently manipulate Bluetooth discovery configuration. This warrants normal patching, but the patch evidence does not support Important-class treatment. 5. One-sentence report phrase A race in Bluetooth discovery UUID filter state can leave a nonzero UUID count with a NULL UUID pointer, allowing nearby Bluetooth advertising traffic to trigger a kernel NULL dereference and denial of service when local discovery configuration is changed concurrently. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Confirm the exact privilege check and namespace scope for the Bluetooth management command that starts service discovery, and determine whether untrusted local users or delegated container services can access the affected Bluetooth HCI device and management interface. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: Bluetooth: mgmt: fix 'hdev->discovery.uuids' NULL dereference [ Upstream Commit: f02c01ccd12cb2b8a290077d4c90f29a6e109b16 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f02c01ccd12cb2b8a290077d4c90f29a6e109b16 Changed files: include/net/bluetooth/hci_core.h net/bluetooth/mgmt.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=f02c01ccd12cb2b8a290077d4c90f29a6e109b16 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93247 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93247 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: Not available The Best / paranoid CVSS vector: AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.8 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: 2 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 alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).