From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-64183][LOW] efi: Allocate runtime workqueue before ACPI init Date: Sun, 19 Jul 2026 13:33:17 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-64183 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: 29cd94e678fcb3c4fd0f359deeac6d61334323fc List-Id: CVE: CVE-2026-64183 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: efi: Allocate runtime workqueue before ACPI init Commit: 29cd94e678fcb3c4fd0f359deeac6d61334323fc Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=29cd94e678fcb3c4fd0f359deeac6d61334323fc Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64183 Analysis date: Sun, 19 Jul 2026 13:33:17 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64183 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64183 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-2026-64183 LOW CHECK WITH IMPACT FROM ORIG NN MODERATE 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-476;CWE-665;CWE-754;BEST CVSS score: '4.1';DESCR 'An EFI runtime workqueue initialization ordering bug can allow early ACPI PRM EFI runtime calls to run before efi_rts_wq is allocated. This can result in a NULL pointer dereference during boot or early subsystem initialization, causing a kernel crash or failed boot. For the CVSS the PR:H is used because reliable attacker controlled triggering normally requires control over firmware, ACPI PRM tables, or privileged boot configuration rather than access by an ordinary local user. The issue is not network reachable and is not triggered by packet traffic or a normal remote service interface. Impact is denial of service only, with no supported evidence of information disclosure, memory corruption beyond NULL dereference, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) YES NULLPTR INIT DEBUGFS LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 1. ActionableScore * Conservative score: 1 * Paranoid score: 1 * Final recommended bucket: **Ordinary Moderate / Low-like**:: 2. Signal breakdown * Firmware-mediated external influence: +1. The trigger depends on early ACPI PRM or EFI runtime behavior coming from firmware or platform tables. * Reliable kernel crash / strong DoS: +1. The described failure is a NULL pointer dereference before the EFI runtime workqueue exists, potentially causing boot or early-init failure. * Availability impact realistic: +1. Failed boot or early subsystem crash is a real availability impact on affected platforms. * Requires admin/root/firmware/boot configuration control: -2. A normal local user cannot reliably shape ACPI PRM tables, firmware behavior, or boot-time EFI runtime ordering. * Rare/difficult-to-reach configuration: -1. ACPI PRM plus this exact initcall ordering is platform/configuration dependent rather than broadly user-triggerable. 3. Reachability analysis The bug is triggered during boot or early subsystem initialization when ACPI PRM invokes EFI runtime services before the runtime workqueue is allocated. Realistic attacker control generally requires firmware influence, malicious or buggy ACPI PRM tables, or privileged control over boot/platform configuration. It is not network reachable, not reachable through a normal syscall by an unprivileged local user, and namespaces or containers do not materially reduce the privilege requirement. 4. Severity interpretation This behaves like a platform-dependent DoS or boot reliability issue, not an Important-class kernel vulnerability. The concrete primitive is a NULL pointer dereference, with no evidence of UAF, OOB write, stale callback, object reuse, information disclosure, integrity corruption, or privilege escalation. Theoretical impact is limited to availability unless an attacker already controls firmware or boot configuration. 5. One-sentence report phrase An EFI runtime workqueue init ordering bug can allow early ACPI PRM EFI runtime calls to hit a NULL pointer dereference during boot or early subsystem initialization, causing a local platform-dependent DoS but not a realistic unprivileged or remote attack. 6. Manual review recommendation NO MANUAL CHECK NEEDED. The patch and commit support only a NULL dereference availability issue in an early firmware-mediated path, with high privilege or platform-control requirements and no memory corruption primitive beyond the NULL dereference. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: efi: Allocate runtime workqueue before ACPI init Commit: 29cd94e678fcb3c4fd0f359deeac6d61334323fc Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=29cd94e678fcb3c4fd0f359deeac6d61334323fc Commit description: Since commit 5894cf5 ("acpi/prmt: Use EFI runtime sandbox to invoke PRM handlers") ACPI PRM calls are delegated to a workqueue which runs in a kernel thread, making it easier to detect and mitigate faulting memory accesses performed by the firmware. Rafael reports that such PRM accesses may occur before efisubsys_init() executes, which is where the workqueue is allocated, leading to NULL pointer dereferences. Since acpi_init() [which triggers the early PRM accesses] executes as a subsys_initcall() as well, and has its own dependencies that may be sensitive to initcall ordering, deferring acpi_init() is not an option. So instead, split off the workqueue allocation into its own postcore initcall, as this is the only missing piece to allow EFI runtime calls to be made. This ensures that EFI runtime call (including PRM calls) are accessible to all code running at subsys_initcall() level. Cc: Fixes: 5894cf5 ("acpi/prmt: Use EFI runtime sandbox to invoke PRM handlers") Reviewed-by: Rafael J. Wysocki (Intel) Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman Changed files: drivers/firmware/efi/efi.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=29cd94e678fcb3c4fd0f359deeac6d61334323fc ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64183 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64183 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: Not available 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: 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).