From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-53314][LOW] padata: Put CPU offline callback in ONLINE section to allow failure [ Upstream Date: Fri, 26 Jun 2026 16:02:48 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-53314 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: 65dae8b34f0810f3fa9f77c4c63650cd20820693 List-Id: CVE: CVE-2026-53314 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: padata: Put CPU offline callback in ONLINE section to allow failure [ Upstream Commit: 65dae8b34f0810f3fa9f77c4c63650cd20820693 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=65dae8b34f0810f3fa9f77c4c63650cd20820693 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53314 Analysis date: Fri, 26 Jun 2026 16:02:48 -0400 ActionableScore: 0 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-2026-53314 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53314 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-2026-53314 LOW CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';CWE-703;CWE-754;CWE-755;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.4';DESCR 'padata registered its CPU offline handling in a hotplug teardown state where callback failure is not allowed. If padata replacement fails during CPU offline, the kernel can report a DEAD callback error warning because the callback returns an error after the hotplug core can no longer handle failure. For the CVSS the PR:H is used because reliable triggering normally requires administrative control of CPU hotplug, such as changing CPU online state. The issue is not network reachable and is triggered through local CPU hotplug control rather than packet traffic or a remote protocol. Impact is mainly availability, including warnings, failed CPU offline operations, and possible kernel crash only on systems that treat warnings as fatal.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0) YES INIT WARNONLY HARDWARE SYZBOT NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 1. ActionableScore * Conservative score: 0 * Paranoid score: 0 * Final recommended bucket: **Ordinary Moderate / Low-like**:: 2. Signal breakdown * Availability impact realistic: +1. CPU offline can fail with a DEAD callback warning, and systems with panic_on_warn could turn this into a crash. * Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2. Reliable triggering requires CPU hotplug control, such as changing CPU online state. * No remote reachability: +0. This is not packet-triggered or network-facing. * No memory corruption primitive: +0. The patch fixes callback placement and error-handling semantics, not UAF, OOB, double-free, refcount misuse, or type confusion. * WARN_ON continuation rule: no strong DoS bonus. The commit shows a warning from an invalid hotplug callback failure path, not a guaranteed kernel crash or corruption primitive. 3. Reachability analysis The bug is triggered through local CPU hotplug operations. In normal deployments this requires administrative privileges or equivalent control over CPU online/offline state. Namespaces and containers usually do not expose host CPU hotplug control to unprivileged users, so PR remains high in practical terms. The padata subsystem is kernel core infrastructure, but this specific failure path depends on CPU hotplug and padata instance replacement failure, so realistic exploitation is limited. 4. Severity interpretation This behaves like a Low-like or ordinary Moderate availability issue, not an Important-class vulnerability. Theoretical impact is limited to warnings, failed CPU offline, or panic_on_warn crash behavior. There is no evidence in the patch of memory corruption, privilege escalation, confidentiality impact, or integrity impact. 5. One-sentence report phrase padata placed a CPU offline callback in a hotplug teardown state where failure is not allowed, allowing administrative CPU offline operations to trigger a DEAD callback warning and possible availability impact on panic_on_warn systems. 6. Manual review recommendation NO MANUAL CHECK NEEDED. The issue is admin-triggered CPU hotplug error handling with no demonstrated memory corruption, no network exposure, and no privilege escalation path. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: padata: Put CPU offline callback in ONLINE section to allow failure [ Upstream Commit: 65dae8b34f0810f3fa9f77c4c63650cd20820693 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=65dae8b34f0810f3fa9f77c4c63650cd20820693 Changed files: kernel/cpu.c include/linux/cpuhotplug.h include/linux/padata.h kernel/padata.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=65dae8b34f0810f3fa9f77c4c63650cd20820693 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53314 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53314 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:L/PR:H/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.4 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).