From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98290][MODERATE REGULAR] Bluetooth: RFCOMM: avoid socket lock inversion in listener cleanup [ Upstream Date: Sat, 10 Oct 2026 19:10:42 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98290 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: 3 X-AL-KERNEL-ActionableScore-Lower: 2 X-AL-KERNEL-Commit: eb4adaa46e4c9e6efa7be3ce06398f4d7c39b57c List-Id: CVE: CVE-2026-98290 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: Bluetooth: RFCOMM: avoid socket lock inversion in listener cleanup [ Upstream Commit: eb4adaa46e4c9e6efa7be3ce06398f4d7c39b57c Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eb4adaa46e4c9e6efa7be3ce06398f4d7c39b57c Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98290 Analysis date: Sat, 10 Oct 2026 19:10:42 -0400 ActionableScore: 3 ActionableScore lower bound: 2 Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98290 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98290 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-2026-98290 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98290 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=MODERATE RESULT=DIFF (independent Legacy and Aegis differ; FINAL: MODERATE, Aegis: 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:N/I:N/A:H';*CWE-833;CWE-667;CWE-362;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.3';DESCR 'A lock order inversion in Bluetooth RFCOMM listener cleanup can deadlock because the cleanup path takes a child socket lock before rfcomm_mutex while the RFCOMM worker can take the same locks in the reverse order. Triggering requires an RFCOMM listening socket to be cleaned up while connection or DLC state processing is active. A nearby Bluetooth peer may contribute to the race by initiating RFCOMM connections during listener shutdown, although the peer does not normally control the exact cleanup timing. For the CVSS the PR:N value is used for the paranoid adjacent network scenario because a nearby peer may send Bluetooth connection traffic without executing code on the target. AC:H applies because successful triggering depends on a narrow concurrency window and an externally triggered connection overlapping local listener cleanup. Impact is denial of service through a possible deadlock or stalled RFCOMM processing. The analyzed code does not provide a UAF, out of bounds access, information disclosure, or write primitive, so confidentiality and integrity remain unaffected.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) MAYBE REMOTE DEADLOCK DANGER SIMPLEFIX NETWORK LINUS SYZBOT MEMORY DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=NO AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw conservative score: 2 * Conservative score: 2 * Raw paranoid score: 3 * Paranoid score: 3 * No floor or cap applied. * Final recommended bucket: **Borderline / manual review recommended**:: 2. Signal breakdown Conservative signals: * +1 Local unprivileged trigger. The owner of an RFCOMM listening socket can invoke shutdown without host-administrator authority. * +1 Strong DoS. The concrete ABBA lock-order inversion can deadlock RFCOMM processing when listener cleanup overlaps connection or DLC-state handling. * Total: 2. Additional paranoid signal: * +1 Firmware-mediated external influence. A nearby Bluetooth peer can generate incoming RFCOMM connection activity through the Bluetooth controller while listener cleanup occurs. * Total: 3. Not awarded: * Direct remote reachability +2 was not awarded because a nearby peer cannot independently force the local listener-shutdown stage. * No race penalty was applied. Concurrency is required, but the evidence does not establish a one-shot or exceptionally uncontrollable timing window. * No UAF, OOB access, double release, refcount corruption, controlled reclaim, arbitrary write, disclosure, or authorization bypass is established. * No extra Availability point was awarded because the stalled RFCOMM path is the same deadlock consequence. * B5-R does not apply because there is no retry-accumulated OOB write. * B3-PENDING does not apply because no shared-backing write exists. * B4-PENDING does not apply because no DENY-to-ALLOW authorization decision changes. 3. Reachability analysis A local process that owns an RFCOMM listening socket can initiate cleanup through socket shutdown while RFCOMM worker activity handles an incoming connection or DLC transition. RFCOMM socket shutdown itself does not require host UID 0 or host-admin-equivalent capability, so HostAdminRequired=NO and RequiresHostUID0=NO. A nearby Bluetooth peer can influence the worker side by initiating connections, but cannot independently control the local shutdown stage. The strongest adjacent scenario is therefore a compound timing condition rather than a fully remote trigger. An operational Bluetooth controller and configured Bluetooth stack are prerequisites, but this does not establish rare hardware or attacker-required host-admin setup. No namespace capability is required or relevant to the demonstrated socket operation, so NamespaceScopedPrivilege=NO. Repeated connection and listener create-close cycles appear possible, but the exact deadlock reliability is not demonstrated. 4. Primitive and severity interpretation The exact primitive is an ABBA lock-order inversion. Listener cleanup acquired the child socket lock before rfcomm_mutex, while the RFCOMM worker could acquire rfcomm_mutex before the socket lock. This can leave both paths waiting on each other. The patch also addresses a state race introduced by removing the child lock. It sets the listener to BT_CLOSED while still protected, preventing rfcomm_connect_ind from adding children after queue draining begins. There is no post-lifetime object use. The accept queue retains a child reference, and bt_accept_dequeue protects unlinking and parent-pointer clearing. Therefore this is not a UAF, repeated lifetime mutation, or memory-corruption primitive. PrimitiveClass=CLASS_C because the demonstrated behavior is deadlock and availability loss without independently useful corruption. ImportantCandidate=NO because no exploitation leverage remains after excluding the DoS. AutoDowngradeAllowed=YES because no unresolved lifetime, ownership, authorization, or corruption primitive exists. Operational severity is borderline Moderate, primarily affecting systems actively using RFCOMM listeners. 5. One-sentence report phrase A lock-order inversion between RFCOMM listener cleanup and worker-side connection processing can deadlock Bluetooth processing when socket shutdown overlaps an incoming connection, causing a local or adjacent-assisted denial of service without demonstrated memory corruption. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Review is appropriate to confirm whether the deadlock can stall only RFCOMM processing or broader kernel work, and whether a nearby peer can reliably synchronize with listener shutdown, but no Important-preserving primitive is established. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: Bluetooth: RFCOMM: avoid socket lock inversion in listener cleanup [ Upstream Commit: eb4adaa46e4c9e6efa7be3ce06398f4d7c39b57c Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eb4adaa46e4c9e6efa7be3ce06398f4d7c39b57c Changed files: net/bluetooth/rfcomm/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=eb4adaa46e4c9e6efa7be3ce06398f4d7c39b57c ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98290 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98290 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:H 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 alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).