From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80676][MODERATE 7.0] Drivers: hv: vmbus: use generic driver_override infrastructure [ Upstream Date: Fri, 28 Aug 2026 05:30:20 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80676 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 5 X-AL-KERNEL-ActionableScore-Lower: 4 X-AL-KERNEL-Commit: d1cb12ae81d2f7a58b0b1cfb51862afca98e6058 List-Id: CVE: CVE-2026-80676 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: Drivers: hv: vmbus: use generic driver_override infrastructure [ Upstream Commit: d1cb12ae81d2f7a58b0b1cfb51862afca98e6058 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d1cb12ae81d2f7a58b0b1cfb51862afca98e6058 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80676 Analysis date: Fri, 28 Aug 2026 05:30:20 -0400 ActionableScore: 5 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80676 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80676 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 7.0 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-2026-80676 MODERATE CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'A race in the Hyper V vmbus driver_override handling can cause a use after free because the bus match callback may read driver_override without the device lock while another path replaces or frees the same string through sysfs. The vulnerable access occurs during driver probing through __driver_attach, where match() is intentionally called without the device lock, so concurrent override updates can leave vmbus_match using stale memory. For the CVSS the PR:L is used for the paranoid score because practical exposure may include delegated device management, service accounts, container root, or reduced capability root rather than only full host administrator access. The issue is local and is not directly network reachable. Impact is at least local denial of service via kernel crash. In worst case it may allow limited confidentiality or integrity impact due to kernel use after free behavior, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5) YES LOCK UAF HARDWARE LINUS DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=4 1. ActionableScore * Conservative score: 4 * Paranoid score: 5 * Final recommended bucket: **Actionable Moderate at minimum**:: 2. Signal breakdown * Memory corruption, weak/indirect corruption candidate: +1. The patch explicitly says unlocked driver_override access can cause UAF, but the visible primitive is stale string read/strcmp rather than controlled reclaim or overwrite. * Real lifetime corruption: +1. The bug is a real lifetime race between driver_override replacement/free and match callback access. * Reliable kernel crash / strong DoS: +1. A UAF in a driver match path can realistically produce KASAN splat, Oops, or kernel crash, although reliable exploitation is not demonstrated. * Privileged kernel/device-management memory corruption path: +1. The corruption occurs in the driver binding/probing path for Hyper V vmbus devices. * Hard or unreliable race / special timing required: -1. Triggering requires racing sysfs override changes with __driver_attach probing. * Requires admin/root/CAP_* in typical deployments: -1 conservative refinement, not -2 for paranoid scoring. driver_override and device binding are usually privileged, but reduced capability root, service accounts, or delegated device management can make the practical boundary weaker than full host root. 3. Reachability analysis The trigger is local through device driver_override manipulation and driver probing or rebinding. In typical deployments this is root or administrator controlled, so the conservative score treats it as privileged local. Namespaces and containers usually do not expose host vmbus device binding to untrusted users, but environments with delegated device management, reduced capability root, or service automation may lower the effective privilege barrier. The issue is not network reachable. It is relevant mainly on Hyper V guests or systems using vmbus devices. 4. Severity interpretation This is not an ordinary cleanup bug because the commit explicitly identifies a UAF caused by unlocked access to driver_override. At the same time, the visible primitive is race dependent and appears limited to stale pointer read/use during matching, with no demonstrated attacker controlled reclaim, write primitive, callback hijack, or type confusion. Realistic impact is local DoS. Paranoid handling keeps it actionable because kernel lifetime bugs in driver binding paths are historically worth manual review. 5. One-sentence report phrase A local race in Hyper V vmbus driver_override handling can let the driver match path read a freed override string during __driver_attach, causing a UAF and potential kernel crash, with paranoid impact treated as Actionable Moderate because reduced privilege device management scenarios may make PR lower than full host root. 6. Manual review recommendation MANUAL CHECK REQUIRED. The patch explicitly fixes a UAF, and although practical LPE is not demonstrated, the lifetime race occurs in kernel driver binding logic and should not be auto-closed. YES REQUIRES MANUAL CHECK ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: Drivers: hv: vmbus: use generic driver_override infrastructure [ Upstream Commit: d1cb12ae81d2f7a58b0b1cfb51862afca98e6058 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d1cb12ae81d2f7a58b0b1cfb51862afca98e6058 Changed files: drivers/hv/vmbus_drv.c include/linux/hyperv.h 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=d1cb12ae81d2f7a58b0b1cfb51862afca98e6058 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80676 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80676 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:H/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 5.8 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: 4 Paranoid ActionableScore: 5 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 7.0 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).