From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-93150][MODERATE REGULAR] cgroup/cpuset: Make nr_deadline_tasks an atomic_t [ Upstream Date: Fri, 18 Sep 2026 07:10:01 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-93150 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: 3 X-AL-KERNEL-ActionableScore-Lower: 2 X-AL-KERNEL-Commit: e422b32e6a57269ca8164c60674a78bee85cf5fb List-Id: CVE: CVE-2026-93150 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: cgroup/cpuset: Make nr_deadline_tasks an atomic_t [ Upstream Commit: e422b32e6a57269ca8164c60674a78bee85cf5fb Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e422b32e6a57269ca8164c60674a78bee85cf5fb Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93150 Analysis date: Fri, 18 Sep 2026 07:10:01 -0400 ActionableScore: 3 ActionableScore lower bound: 2 Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93150 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93150 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-2026-93150 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-93150 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:L/UI:N/S:U/C:N/I:L/A:H';CWE-362;CWE-667;CWE-682;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '5.3';DESCR 'A race in cgroup/cpuset SCHED_DEADLINE accounting can corrupt nr_deadline_tasks because scheduler updates and cpuset attach updates may modify the same counter under different locks. The corrupted counter can make later cpuset and deadline bandwidth operations use incorrect state, which may affect scheduling policy decisions and system availability. For the CVSS the PR:L is used in the paranoid score because reliable triggering may be possible for a local actor with delegated cgroup control, container root, service account privileges, or relevant scheduling capabilities rather than full host administrator privileges. The issue is not network reachable and requires local control plane activity involving sched_setscheduler and cpuset attach or migration. Impact is mainly denial of service or scheduling policy inconsistency. No concrete UAF, OOB access, information leak, or arbitrary write primitive is visible from this patch, so confidentiality impact is not assigned.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) YES SIMPLEFIX RACE LINUS NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 2 * Conservative score: 2. No floor or cap applied. * Raw paranoid score: 3 * Paranoid score: 3. No floor or cap applied. * Final recommended bucket: **Borderline / manual review recommended**:: 2. Signal breakdown Conservative positive signals: * +1: concrete unsynchronized kernel accounting race. nr_deadline_tasks can be updated concurrently under different locks, so the counter can become incorrect. * +1: plausible scheduling or availability impact. The corrupted counter is used for SCHED_DEADLINE cpuset accounting and root domain bandwidth update decisions, so wrong state can lead to incorrect later scheduler or cpuset operations. Paranoid additional signal: * +1: unresolved scheduler control-plane consequence. The commit states this is a partial low hanging fruit fix and does not cover all related races, so manual review of practical impact is justified. Non-awarded signals: * Real UAF not awarded. The patch does not show stale object use after free. * Controlled reclaim not demonstrated. * Arbitrary write not demonstrated. * Kernel information disclosure not demonstrated. * Concrete authorization bypass not demonstrated. * Local unprivileged trigger not awarded because the complete sched_setscheduler plus cpuset attach or migration trigger path is not proven reachable by an ordinary user. * Host-admin penalty not applied because host-admin-equivalent privilege is not positively established from the supplied evidence. * Race penalty not applied because the prompt requires concrete evidence of a narrow or externally uncontrollable timing window, not merely the presence of a race. * Extra availability point not awarded because no crash, panic, persistent host-wide outage, or resource exhaustion is demonstrated. * Concrete repeated release/refcount signal not awarded. There is no first lifetime release, surviving exact dangling reference, or second lifetime mutation. 3. Reachability analysis The likely trigger requires local control-plane activity involving SCHED_DEADLINE policy changes and cpuset task attach or migration. SCHED_DEADLINE operations commonly require elevated scheduling privilege such as CAP_SYS_NICE, and cpuset manipulation depends on cgroup delegation and controller permissions. HostAdminRequired is UNKNOWN because the supplied patch does not prove that full host administrator privilege is required for the complete vulnerable sequence, but it also does not prove ordinary unprivileged reachability. NamespaceScopedPrivilege is UNKNOWN. Cgroups and cpuset delegation may exist in some environments, but the supplied evidence does not establish that all required stages are attacker-reachable inside a namespace or delegated container context. No direct network trigger is present. No special hardware requirement is present. The race is concurrent scheduler and cpuset accounting activity, but the supplied evidence does not establish a very hard one-shot timing condition. 4. Primitive and severity interpretation The exact primitive is a data race on a scheduler/cpuset accounting counter. The bug can corrupt nr_deadline_tasks, which can then cause incorrect scheduler or cpuset decisions later. This is not an active structured UAF and not fixed stale storage. It is a logic/accounting race with invalid kernel state. There is no concrete memory lifetime violation, no OOB access, no double free, no repeated refcount operation, and no demonstrated attacker-controlled kernel memory corruption. PrimitiveClass is CLASS_C because the demonstrated issue is primarily corrupted accounting and invalid downstream behavior without an independently useful corruption primitive. Demonstrated consequence: incorrect SCHED_DEADLINE cpuset accounting and possible incorrect later operations. Speculative consequence: broader scheduling disruption or availability impact if the corrupted counter causes wrong root domain bandwidth handling. Privilege escalation is not supported by the supplied patch. ImportantCandidate is NO because there is no Class A primitive and no strong Class B lifetime or corruption primitive requiring Important-vs-Moderate preservation. AutoDowngradeAllowed is YES because the issue is an accounting race without demonstrated memory corruption, authorization bypass, concrete repeated lifetime mutation, or protected resource access. Manual review is still recommended because the affected area is scheduler/cgroup code and the fix is explicitly partial. Likely operational severity: ordinary to borderline Moderate, not Important based on supplied evidence. 5. One-sentence report phrase A race in cgroup cpuset SCHED_DEADLINE accounting can corrupt nr_deadline_tasks during concurrent scheduler and cpuset attach updates, causing incorrect scheduler state and possible local denial of service or policy inconsistency without a demonstrated UAF, arbitrary write, information leak, or privilege escalation primitive. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: scheduler and cgroup accounting races can have non-obvious downstream effects, and the commit explicitly says this fix does not cover all related races, but the supplied patch does not establish a memory corruption or authorization-bypass primitive requiring mandatory Important-class review. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: cgroup/cpuset: Make nr_deadline_tasks an atomic_t [ Upstream Commit: e422b32e6a57269ca8164c60674a78bee85cf5fb Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e422b32e6a57269ca8164c60674a78bee85cf5fb Changed files: kernel/cgroup/cpuset-internal.h kernel/cgroup/cpuset.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=e422b32e6a57269ca8164c60674a78bee85cf5fb ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93150 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93150 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:L/A:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H The Best / paranoid CVSS score: 5.3 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: 2 Paranoid ActionableScore: 3 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).