From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-90194][LOW] ACPI: scan: fix bus ID cleanup on device_add() failures [ Upstream Date: Thu, 17 Sep 2026 13:52:34 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-90194 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: 0 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 8cc2017aa804f157e717b5fd471e50fbddfec654 List-Id: CVE: CVE-2026-90194 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: ACPI: scan: fix bus ID cleanup on device_add() failures [ Upstream Commit: 8cc2017aa804f157e717b5fd471e50fbddfec654 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8cc2017aa804f157e717b5fd471e50fbddfec654 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90194 Analysis date: Thu, 17 Sep 2026 13:52:34 -0400 ActionableScore: 0 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: ACPI device registration failure can leave bus ID bookkeeping and instance numbers allocated after `device_add()` fails, but exploitation appears to require host administrative or platform level control and the impact is limited to resource leakage or availability degradation after repeated failures. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-90194 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90194 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-2026-90194 LOW https://www.kernelcve.org/list/?q=CVE-2026-90194 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:H/UI:N/S:U/C:N/I:N/A:H';*CWE-772;CWE-404;*CWE-401;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.1';DESCR 'ACPI device registration can leak bus ID bookkeeping when device_add() fails after acpi_device_set_name() has allocated an instance ID and linked a new bus ID entry. This leaves the instance number consumed and can keep stale internal accounting after a failed add path. For the CVSS the PR:H is used because reliable triggering normally requires administrative control over ACPI device enumeration, hotplug, firmware supplied devices, or equivalent platform level control. The issue is not network reachable and is not triggered by packet processing. Impact is mainly availability through small resource leakage or exhausted ACPI instance bookkeeping after repeated failures. No memory corruption, information leak, or privilege escalation primitive is evident from the code change.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) YES LOCK SIMPLEFIX HARDWARE NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=YES NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES ## 1. ActionableScore * Raw conservative score: -1 * Conservative score: 0 * Raw paranoid score: 0 * Paranoid score: 0 * Applied conservative floor/cap: minimum score floor -1 -> 0 * Applied paranoid floor/cap: none * Final recommended bucket: **Ordinary Moderate**:: ## 2. Signal breakdown Conservative signals: * +1 Concrete persistent kernel resource/reference leak. The rollback path after `device_add()` failure leaves ACPI bus ID bookkeeping and the allocated instance number behind. * -2 Host-admin-equivalent or platform-level control required. Reliable triggering appears to require ACPI enumeration, ACPI hotplug, firmware/platform behavior, or equivalent administrative control. Paranoid signals: * +1 Concrete persistent kernel resource/reference leak. Same as conservative. * +1 Possible availability degradation from repeated failed ACPI device registration consuming instance IDs or accumulating stale bookkeeping. * -2 Host-admin-equivalent or platform-level control required. Material non-awarded signals: * No UAF is established. * No repeated release/refcount mutation is established. * No arbitrary write or controlled kernel corruption is established. * No confidentiality or integrity impact is supported. * No security-boundary bypass is established. * No remote/network reachability is established. * No extra DoS point is awarded for a kernel crash because no crash or panic primitive is shown. * No ImportantCandidate signal is awarded because this is a cleanup/resource-accounting bug, not a corruption or authorization primitive. ## 3. Reachability analysis The vulnerable path is in ACPI device registration rollback after `acpi_device_set_name()` succeeds but `device_add()` fails. This is not an ordinary syscall, packet-processing, namespace, or user-data-plane interface. A realistic attacker would need to influence ACPI device enumeration or hotplug behavior, cause repeated registration failures, or control firmware/platform-level device presentation. That is host-admin-equivalent or platform-level control in normal deployments. No evidence shows that the complete trigger chain is namespace-scoped. No prior attacker-obtainable namespace capability is relevant. No network trigger is present. No special race is required, but the required failure path is not normally available to an unprivileged local user. ## 4. Primitive and severity interpretation The exact primitive is a missing cleanup of ACPI bus ID bookkeeping and consumed instance IDs after an error path. This is a resource/reference bookkeeping leak. This is not active structured stale-object use. It is not fixed stale storage being accessed after free. It is not a cleanup UAF. It is not a concrete repeated release/refcount case because there is no first release that can end object lifetime followed by a second lifetime mutation on the same dangling reference. PrimitiveClass is `NONE` because no meaningful kernel corruption, lifetime UAF, ownership violation, or authorization bypass is established. The demonstrated consequence is stale accounting and possible resource leakage. The speculative consequence is availability degradation after repeated failures, but this remains low practical risk due to required ACPI/platform control. ImportantCandidate is `NO` because there is no unresolved memory-corruption or boundary-bypass primitive. AutoDowngradeAllowed is `YES` because the issue is a constrained cleanup/resource leak and does not require manual Important-vs-Moderate exploitation analysis. Likely operational severity is Low or ordinary Moderate-like. ## 5. One-sentence report phrase ACPI device registration failure can leave bus ID bookkeeping and instance numbers allocated after `device_add()` fails, but exploitation appears to require host administrative or platform level control and the impact is limited to resource leakage or availability degradation after repeated failures. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED Reason: no UAF, memory corruption, authorization bypass, network reachability, or plausible privilege escalation primitive is established. ## 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ACPI: scan: fix bus ID cleanup on device_add() failures [ Upstream Commit: 8cc2017aa804f157e717b5fd471e50fbddfec654 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8cc2017aa804f157e717b5fd471e50fbddfec654 Changed files: drivers/acpi/scan.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=8cc2017aa804f157e717b5fd471e50fbddfec654 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-90194 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90194 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:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.1 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: 0 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).