From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-93260][MODERATE REGULAR] powerpc/xive: propagate IPI init errors to prevent use-after-free [ Upstream Date: Thu, 24 Sep 2026 19:57:36 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-93260 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: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: c554a8d376d5aea1b237ed6bef6f9fbfc550e67f List-Id: CVE: CVE-2026-93260 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: powerpc/xive: propagate IPI init errors to prevent use-after-free [ Upstream Commit: c554a8d376d5aea1b237ed6bef6f9fbfc550e67f Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c554a8d376d5aea1b237ed6bef6f9fbfc550e67f Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93260 Analysis date: Thu, 24 Sep 2026 19:57:36 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93260 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93260 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-2026-93260 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-93260 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:L/I:L/A:H';*CWE-416;CWE-252;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.2';DESCR 'A use-after-free can occur in the PowerPC XIVE SMP initialization path when xive_init_ipis fails and frees the global xive_ipis array, but xive_smp_probe continues and calls xive_setup_cpu_ipi. The resulting access to freed state can crash the kernel or prevent correct SMP initialization. For the CVSS the PR:H is used because reliable triggering normally requires control over privileged boot configuration or early resource allocation conditions. The issue is not network reachable and affects PowerPC systems using the XIVE interrupt controller. Impact is primarily denial of service. A limited confidentiality and integrity impact is retained only for the paranoid score because this is a real use-after-free, although the available patch context does not demonstrate a controlled reuse or write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) YES INIT ERRORPATH UAF HARDWARE LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_B RealUAF=YES HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 3 * Conservative score: 1 * Raw paranoid score: 3 * Paranoid score: 1 * Applied conservative reduction: 3 -> 1 due to a concrete rare-hardware requirement. The affected code is limited to PowerPC systems using the XIVE interrupt controller. * Applied paranoid reduction: 3 -> 1 for the same reason. * Final recommended bucket: **Ordinary Moderate**:: The patch establishes a real UAF, but the supplied evidence only shows an early boot initialization failure followed by a dereference of a freed global allocation. No attacker-controlled trigger, post-free reuse, replacement, write, disclosure, or privilege-boundary effect is established. 2. Signal breakdown Positive signals: * +2 Real UAF or active lifetime violation. xive_init_ipis can fail and free the global xive_ipis array. xive_smp_probe then continues into xive_setup_cpu_ipi, which dereferences the freed global pointer. * +1 Reliable kernel crash or strong DoS. Dereferencing a freed global IPI array during SMP initialization can cause a kernel fault, boot failure, or failure to correctly initialize SMP. Negative signals: * -2 Rare hardware-only requirement. The vulnerable path is specific to PowerPC PowerNV or pSeries platforms with the XIVE interrupt controller enabled. The patch does not establish reachability on common non-PowerPC systems. Important non-awarded signals: * Remote reachability not established. This is an early boot initialization path and no network-controlled input reaches the failure sequence. * Local unprivileged trigger not established. The supplied evidence does not show that an ordinary user can induce irq_domain_alloc_irqs failure during early XIVE initialization. * Host-admin privilege requirement is not positively established. The necessary attacker privilege boundary is unresolved, so no host-admin penalty is applied. * Controlled reclaim or attacker-controlled replacement of xive_ipis storage is not demonstrated. * Arbitrary or directed kernel write is not demonstrated. * Structured stale-object exploitation leverage is not awarded. The stale object is a fixed global IPI array used during initialization, and the shown stale operation is a dereference rather than meaningful continued structured processing under attacker influence. * Weak LPE concern is not awarded. A generic UAF alone is insufficient. * Confidentiality and integrity impact are not awarded. There is no demonstrated disclosure, unauthorized modification, controlled post-free contents, or security-boundary bypass. * Extra Availability is not awarded because the boot failure or kernel crash is already counted as the strong DoS signal. * No repeated release or refcount mutation exists. The patch shows free followed by stale dereference, not a second put, release, free, or refcount operation on the same dangling reference. * FLOOR 5 is not applied. This is a constrained initialization-time UAF involving fixed global storage, with no demonstrated attacker-controlled reuse or second lifetime mutation. 3. Reachability analysis The affected execution path runs during PowerPC SMP initialization in pnv_smp_probe or pSeries_smp_probe when XIVE is enabled. The initial failure occurs in xive_init_ipis, for example when irq_domain_alloc_irqs fails. The subsequent stale dereference occurs before normal userspace workload processing. No supplied evidence establishes that an ordinary local user, container user, namespace administrator, service account, or remote attacker can reliably cause the required allocation failure during this boot-time sequence. The complete trigger is not namespace-scoped. Network namespaces and delegated capabilities are not relevant to XIVE interrupt-controller initialization. The hardware requirement is material. The issue affects PowerPC PowerNV or pSeries environments that use XIVE. No boot option, firmware manipulation path, resource-pressure mechanism, or attacker-controlled configuration prerequisite is demonstrated by the supplied patch. 4. Primitive and severity interpretation The exact primitive is a real use-after-free. A global xive_ipis allocation is freed after xive_init_ipis fails, while the caller ignores that failure and proceeds to xive_setup_cpu_ipi, which uses the stale global pointer. This is fixed stale initialization storage rather than an attacker-controlled active structured object. The visible path is an ordered error sequence during boot initialization, not a concurrent repeated lifetime transition. There is no concrete second release, refcount decrement, callback dispatch, object substitution, controlled reclaim, arbitrary write, or information-disclosure path. The appropriate classification is CLASS_B because the patch directly establishes a post-free dereference. However, the available evidence supports kernel crash or boot-time DoS only. Potential confidentiality, integrity, privilege escalation, or controlled corruption consequences remain speculative and are not included in the score. ImportantCandidate is NO because the stale use is constrained to a hardware-specific early initialization error path and lacks meaningful demonstrated exploitation leverage beyond the crash. AutoDowngradeAllowed is YES because this is a constrained CLASS_B UAF with no established reuse primitive, no repeated lifetime mutation, no boundary bypass, and no demonstrated below-host-admin attacker path. Likely operational severity is low to ordinary Moderate. Systems running affected PowerPC XIVE hardware should apply the fix, but the patch alone does not justify Important-class treatment. 5. One-sentence report phrase A PowerPC XIVE SMP initialization error can free the global xive_ipis array while later setup code still dereferences it, causing a boot-time kernel crash or SMP initialization failure on affected XIVE systems. 6. Manual review recommendation MANUAL CHECK RECOMMENDED The patch establishes a real UAF, but manual confirmation is needed only to determine whether a realistic attacker-controlled mechanism exists for inducing the early irq-domain allocation failure on an affected PowerPC XIVE platform. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: powerpc/xive: propagate IPI init errors to prevent use-after-free [ Upstream Commit: c554a8d376d5aea1b237ed6bef6f9fbfc550e67f Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c554a8d376d5aea1b237ed6bef6f9fbfc550e67f Changed files: arch/powerpc/platforms/powernv/smp.c arch/powerpc/platforms/pseries/smp.c arch/powerpc/sysdev/xive/common.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=c554a8d376d5aea1b237ed6bef6f9fbfc550e67f ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93260 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93260 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:H/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 5.2 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: 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: 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).