From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99009][LOW] Bluetooth: RFCOMM: connect the session socket without rfcomm_mutex [ Upstream Date: Mon, 26 Oct 2026 16:22:45 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99009 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 4dc3d5a004b8fd59f3c905631dbb18cb601b1b41 List-Id: CVE: CVE-2026-99009 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: Bluetooth: RFCOMM: connect the session socket without rfcomm_mutex [ Upstream Commit: 4dc3d5a004b8fd59f3c905631dbb18cb601b1b41 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4dc3d5a004b8fd59f3c905631dbb18cb601b1b41 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99009 Analysis date: Mon, 26 Oct 2026 16:22:45 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A local low-privilege RFCOMM connect overlapping BR/EDR authentication can trigger a real AB/BA deadlock and disrupt Bluetooth processing without a shown memory-corruption or authorization primitive. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99009 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99009 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: LOW 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-2026-99009 LOW https://www.kernelcve.org/list/?q=CVE-2026-99009 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE AEGIS_AS=1 LEGACY=LOW RESULT=DIFF (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/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:L';BEST CVSS score: '4.7';DESCR 'A real AB BA lock inversion exists between rfcomm_mutex and hdev lock. The HCI authentication or encryption event path holds hdev lock before entering rfcomm_security_cfm and taking rfcomm_mutex, while a local RFCOMM connect holds rfcomm_mutex before L2CAP takes hdev lock. Concurrent execution can deadlock RFCOMM and HCI processing, causing Bluetooth availability loss without a demonstrated memory corruption or information disclosure primitive. For the CVSS the PR:L reflects that reliable triggering requires a local process able to issue an RFCOMM socket connect. AC:H reflects the required timing overlap with BR EDR authentication or encryption processing. A nearby Bluetooth peer may help establish the required link state but cannot trigger the local connect alone. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic and the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 with primitive class CLASS_C and manual review RECOMMENDED. Its independently reconciled impact was MODERATE. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE REMOTE OOB LOCK DANGER INIT NOMEMCHK NETWORK HARDWARE LINUS SYZBOT DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES RequiresHostUID0=NO AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 1 (+1 local low-privilege trigger, +1 Bluetooth-stack deadlock/availability loss, -1 materially timing-dependent overlap). * Conservative score: 1; no floor or cap applied. * Raw paranoid score: 1. * Paranoid score: 1; no stronger corruption or host-wide failure is technically supported. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Local unprivileged trigger: the supplied call path grounds the vulnerable lock order in a userspace RFCOMM `connect()` and describes PR:L rather than host-administrator access. * +1 Availability impact: the real AB/BA inversion can deadlock RFCOMM/HCI processing and impair Bluetooth availability. * -1 Hard timing: actual deadlock requires overlap between local connect and BR/EDR authentication or encryption event processing; observing both lock orders alone only produces the lockdep report. * No memory corruption, UAF, OOB access, repeated lifetime mutation, authorization bypass, confidentiality impact, integrity impact, or host panic is shown. * No remote-reachability bonus: a nearby peer can establish relevant link state but cannot issue the required local RFCOMM connect. * NEW52 B5-R and NEW53 B3-PENDING do not apply: there is no write primitive or shared-backing modification. 3. Reachability analysis A below-host-admin local process able to open and connect an RFCOMM socket can establish one lock order; concurrent HCI authentication/encryption supplies the reverse order. Host UID 0, capabilities, namespace-scoped privileges, and prior host-admin provisioning are not shown as required. Bluetooth hardware and a suitable BR/EDR link are prerequisites, but no rare-hardware penalty is justified. 4. Primitive and severity reading The primitive is a lock-order inversion causing possible subsystem deadlock, classified CLASS_C. The patch removes `rfcomm_mutex -> hdev->lock` by connecting the session socket before taking `rfcomm_mutex`, while adding state handling for the unlocked window. The supported effect is Bluetooth availability loss, not kernel-memory corruption or a protected-state change. Therefore Important candidacy and mandatory review are unwarranted, and automatic Moderate handling is safe. 5. One-sentence report phrase A local low-privilege RFCOMM connect overlapping BR/EDR authentication can trigger a real AB/BA deadlock and disrupt Bluetooth processing without a shown memory-corruption or authorization primitive. 6. Manual review advice NO MANUAL CHECK NEEDED The patch and call chains sufficiently establish a timing-dependent availability-only defect. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: Bluetooth: RFCOMM: connect the session socket without rfcomm_mutex [ Upstream Commit: 4dc3d5a004b8fd59f3c905631dbb18cb601b1b41 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4dc3d5a004b8fd59f3c905631dbb18cb601b1b41 Changed files: include/net/bluetooth/rfcomm.h net/bluetooth/rfcomm/core.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=4dc3d5a004b8fd59f3c905631dbb18cb601b1b41 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99009 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99009 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:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.7 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: 1 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: LOW KPANIC detected for this report: NO Published priority for this report (same as in Subject): LOW 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).