From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-68339][MODERATE REGULAR] Bluetooth: btusb: validate Realtek vendor event length [ Upstream Date: Mon, 10 Aug 2026 15:56:24 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-68339 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: 1 X-AL-KERNEL-Commit: 8de58bfa26e028f99271dde5a92107cd07f5e063 List-Id: CVE: CVE-2026-68339 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: Bluetooth: btusb: validate Realtek vendor event length [ Upstream Commit: 8de58bfa26e028f99271dde5a92107cd07f5e063 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8de58bfa26e028f99271dde5a92107cd07f5e063 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68339 Analysis date: Mon, 10 Aug 2026 15:56:24 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A short Realtek Bluetooth vendor event can cause `btusb_recv_event_realtek()` to read `skb->data[2]` before validating that the byte exists, resulting in a limited kernel out-of-bounds read and possible coredump misclassification, but no supported privilege escalation or remote network attack path is shown. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68339 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68339 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-2026-68339 MODERATE CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L';CWE-125;*CWE-20;CWE-754;Other CVSS 'AV:P/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L';BEST CVSS score: '3.2';DESCR 'A short Realtek Bluetooth vendor event can reach btusb_recv_event_realtek with less than three bytes of event data, while the old classifier reads data byte 2 before validating that the Realtek subevent byte is present. This is a small out of bounds read in the local btusb receive path and may misclassify a malformed event as a Realtek coredump if the adjacent byte has the expected value. For the CVSS the PR:N is used because the attacker does not need an account on the victim once a malicious or compromised Bluetooth USB controller is the input source. The issue is not directly network reachable over Bluetooth packet traffic and normally requires physical device control or compromised local controller firmware. Impact is mainly denial of service or diagnostic misbehavior. In the paranoid score confidentiality is limited because an out of bounds read exists, but there is no supported arbitrary write, UAF, or privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) YES USB SIMPLEFIX SKB DEBUGFS INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like** ## 2. Signal breakdown Conservative signals: * Firmware-mediated external influence: +1. The malformed input is an HCI event delivered by a local Realtek USB Bluetooth controller or its firmware, not a normal remote network packet. * No strong memory corruption primitive: +0. The bug is a one-byte out-of-bounds read from `skb->data[2]`, not an OOB write, UAF, double free, type confusion, or arbitrary write. * No reliable kernel crash shown: +0. The commit describes misclassification as a coredump, not a demonstrated panic or persistent host-wide DoS. * No LPE signal: +0. There is no reclaim, write primitive, callback control, refcount takeover, or attacker-controlled object replacement. * Constrained read-only primitive: -1. The read is small and used only for classification. * Physical or firmware control requirement: effectively limits exposure. I do not apply full remote reachability. Paranoid additional signals: * Confidentiality impact plausible: +1. Because an OOB read exists in kernel memory, a limited confidentiality concern is technically possible, but the patch does not show a user-visible leak path. * Availability impact weakly plausible: +0 or +1 considered, but not counted separately because no reliable crash path is shown. ## 3. Reachability analysis The realistic trigger is a malformed Realtek vendor HCI event received through the local `btusb` driver path. A normal remote Bluetooth peer does not directly control this USB HCI event stream in the same way as a network protocol parser. Practical exploitation would usually require a malicious USB Bluetooth device, compromised controller firmware, or a test setup able to inject malformed HCI events. No local Linux user account is required once the malicious device or firmware is the input source, but the attack is not network-reachable in the usual AV:N sense. Namespaces and containers do not materially lower the requirement, because the vulnerable input originates from the physical or firmware-mediated Bluetooth controller path. Call-site confidence: high for the immediate bug, because the patch directly shows the missing `skb->len` check before `skb->data[2]`. Confidence is lower for downstream impact because the full coredump handling path is not included. ## 4. Severity interpretation This behaves like a low-end memory-safety validation bug, not an Important-class kernel vulnerability. The theoretical issue is an out-of-bounds read and possible coredump misclassification. Realistic exploitation evidence is weak because there is no demonstrated disclosure path, no write primitive, no UAF, no privilege escalation path, and no reliable kernel crash described. The issue should not be treated as remote network-triggerable. It is best triaged as ordinary Moderate or Low-like, with manual review only because kernel OOB reads can sometimes hide secondary effects. ## 5. One-sentence report phrase A short Realtek Bluetooth vendor event can cause `btusb_recv_event_realtek()` to read `skb->data[2]` before validating that the byte exists, resulting in a limited kernel out-of-bounds read and possible coredump misclassification, but no supported privilege escalation or remote network attack path is shown. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Manual review is recommended because this is a kernel out-of-bounds read in a device input path, but the current evidence supports only low practical severity and does not justify Important-class handling. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: Bluetooth: btusb: validate Realtek vendor event length [ Upstream Commit: 8de58bfa26e028f99271dde5a92107cd07f5e063 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8de58bfa26e028f99271dde5a92107cd07f5e063 Changed files: drivers/bluetooth/btusb.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=8de58bfa26e028f99271dde5a92107cd07f5e063 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68339 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68339 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:P/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L The Best / paranoid CVSS score: 3.2 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: 1 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).