From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72334][MODERATE REGULAR] Bluetooth: ISO: fix malformed ISO_END/CONT handling [ Upstream Date: Sat, 15 Aug 2026 10:09:11 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72334 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: 4 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: 990e65eb9387c4ddfa7f68782b6644c2c35d489f List-Id: CVE: CVE-2026-72334 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: Bluetooth: ISO: fix malformed ISO_END/CONT handling [ Upstream Commit: 990e65eb9387c4ddfa7f68782b6644c2c35d489f Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=990e65eb9387c4ddfa7f68782b6644c2c35d489f Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72334 Analysis date: Sat, 15 Aug 2026 10:09:11 -0400 ActionableScore: 4 ActionableScore lower bound: 3 Actionable bucket: Borderline, manual review recommended Manual review required: YES Summary: Malformed Bluetooth ISO_END or ISO_CONT handling can allow malformed adjacent Bluetooth or controller-supplied ISO fragments to leak conn rx_skb or trigger an skb_put panic, causing a kernel denial of service without supported evidence of privilege escalation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72334 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72334 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-2026-72334 MODERATE CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-20;CWE-617;**CWE-400;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.5';DESCR 'Malformed Bluetooth ISO fragmentation can leave conn rx_skb allocated or can drive iso_recv into skb_put with an excessive ISO_END length, leading to a kernel panic. A malformed sequence such as ISO_START, ISO_CONT, ISO_START can leak the receive skb, while an overlong ISO_END can crash the host and a too short ISO_END may be accepted incorrectly. For the CVSS the PR:N is used for the paranoid score because an attacker does not need local privileges if malformed ISO data can be delivered over an adjacent Bluetooth link or through an exposed HCI controller path. The issue is not Internet reachable but it is adjacent network reachable for Bluetooth capable targets and practical exploitation depends on ISO support, controller behavior, and the ability to influence malformed ISO fragments. Impact is denial of service via resource leak or kernel crash, with no supported evidence of privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 4) SKIP CVE-2026-72334 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 84c24fb151fc1179355296d7ff29129ac7c42129 YES NO NO unknown MAYBE REMOTE LEAK NETWORK SKB PACKET DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN6 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: 3 * Paranoid score: 4 * Final recommended bucket: **Borderline, manual review recommended**:: ## 2. Signal breakdown Conservative signals: * Firmware-mediated external influence: +1 The malformed ISO fragments are described as being sent by the Bluetooth controller. A nearby peer may influence this path only if the controller forwards or produces such malformed HCI ISO sequences. * Reliable kernel crash / strong DoS: +1 The commit explicitly states that a too long ISO_END can panic on skb_put. * Availability impact realistic: +1 The failure mode is a host kernel panic, not just a rejected packet or local warning. Paranoid delta: * Remote reachable / network-triggerable: +2 instead of firmware-mediated +1 If malformed ISO traffic can be induced by an adjacent Bluetooth peer rather than only by a faulty or malicious local controller, this becomes adjacent-network reachable. Not awarded: * No generic memory corruption score. skb_put appears to panic on length validation rather than giving a demonstrated controlled overwrite. * No LPE score. The patch does not show reclaim, object replacement, callback control, type confusion, or write primitive. * No confidentiality or integrity impact. The supported impact is leak of conn->rx_skb and kernel panic. ## 3. Reachability analysis The direct malformed input source is the Bluetooth controller delivering ISO fragments into iso_recv. A local unprivileged process is not clearly required, and the meaningful question is whether a remote adjacent Bluetooth device can cause the controller to emit the malformed ISO_START, ISO_CONT, or ISO_END sequence. This is not Internet reachable. It is potentially adjacent-network reachable on Bluetooth-capable systems with ISO support enabled and relevant controller behavior. Namespaces do not meaningfully reduce the attack requirement because the vulnerable path is below normal socket namespace policy once malformed HCI ISO data reaches the host stack. ## 4. Severity interpretation This behaves more like a strong DoS / actionable edge Moderate than an Important memory-corruption issue. The realistic demonstrated impact is kernel panic via malformed Bluetooth ISO fragmentation and resource leak of conn->rx_skb. Theoretical memory corruption is not supported strongly enough because the described skb_put path is a panic condition, not a shown attacker-controlled overwrite. Manual review is still justified because Bluetooth is an adjacent external input path and exploitability depends on controller and over-the-air behavior. ## 5. One-sentence report phrase Malformed Bluetooth ISO_END or ISO_CONT handling can allow malformed adjacent Bluetooth or controller-supplied ISO fragments to leak conn rx_skb or trigger an skb_put panic, causing a kernel denial of service without supported evidence of privilege escalation. ## 6. Manual review recommendation MANUAL CHECK REQUIRED This should not be auto-closed because it is an adjacent Bluetooth input path with an explicit kernel panic condition. The key manual question is whether a nearby Bluetooth peer can reliably induce the malformed HCI ISO sequence on affected controllers, or whether triggering is limited to faulty or malicious local firmware/controller behavior. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: Bluetooth: ISO: fix malformed ISO_END/CONT handling [ Upstream Commit: 990e65eb9387c4ddfa7f68782b6644c2c35d489f Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=990e65eb9387c4ddfa7f68782b6644c2c35d489f Changed files: net/bluetooth/iso.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=990e65eb9387c4ddfa7f68782b6644c2c35d489f ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72334 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72334 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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 6.5 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: 3 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: 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).