From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-68092][LOW] time/jiffies: Register jiffies clocksource before usage [ Upstream Date: Mon, 10 Aug 2026 12:28:05 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-68092 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: 0 X-AL-KERNEL-Commit: fe9bdea65ba231fcfb155031628bb1e8491b5fe0 List-Id: CVE: CVE-2026-68092 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: time/jiffies: Register jiffies clocksource before usage [ Upstream Commit: fe9bdea65ba231fcfb155031628bb1e8491b5fe0 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fe9bdea65ba231fcfb155031628bb1e8491b5fe0 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68092 Analysis date: Mon, 10 Aug 2026 12:28:05 -0400 ActionableScore: 1 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: The jiffies clocksource may be used before registration during early boot, causing time reads to be clamped and producing a long boot delay or boot-time denial of service on affected Xen HVM guests. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68092 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68092 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-2026-68092 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-665;*CWE-664;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.1';DESCR 'The jiffies clocksource can be used during early boot before it is registered, leaving max_delta_raw as 0 and causing time reads to be clamped so time does not progress. On affected Xen HVM guests this can lead to a long boot delay or boot time denial of service, but the patch does not indicate a memory corruption primitive, UAF, OOB access, or privilege escalation path. For the CVSS the PR:H is used because reliable triggering depends on controlling the boot environment, kernel version, or virtual platform configuration rather than on an unprivileged local interface. The issue is not network reachable and has availability impact only.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) SKIP CVE-2026-68092 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 76031d9536a076bf023bedbdb1b4317fc801dd67 YES NO NO unknown MAYBE INIT SIMPLEFIX LINUS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 1 * Final recommended bucket: **Ordinary Moderate / Low-like** ## 2. Signal breakdown Conservative signals: * Requires admin/root/boot-environment control: -2. Reliable triggering depends on kernel version, boot path, and Xen HVM or similar virtual platform behavior, not on an unprivileged runtime interface. * Rare or configuration-dependent trigger: -1. The reported symptom is tied to early boot clocksource ordering on Xen HVM after a specific timekeeping change. * No memory corruption signal: 0. The patch shows initialization ordering only. No UAF, OOB, double free, refcount issue, arbitrary write, or stale pointer primitive is indicated. * No confidentiality or integrity impact: 0. The failure mode is time not progressing during early boot. * Availability impact exists but is not attacker-reachable in normal operation: +1 at most. The realistic effect is long boot delay or boot-time DoS. Paranoid adjustment: * Boot-time availability DoS: +1. If the system reliably stalls during boot on affected Xen HVM configurations, this can be operationally significant, but still not security-boundary crossing. ## 3. Reachability analysis The issue is not network reachable and is not triggerable by a normal local unprivileged user after the system has booted. Practical triggering requires controlling or selecting an affected kernel and boot environment, or operating an affected Xen HVM configuration. Namespaces and containers do not meaningfully reduce the privilege requirement because the bug occurs before normal userspace/container attack surfaces are available. Call-site confidence: high. The patch directly changes `clocksource_default_clock()` and the commit explains the early use before registration. ## 4. Severity interpretation This behaves like a low-risk initialization/order bug with availability impact only. It does not behave like an actionable Moderate or Important kernel vulnerability because there is no memory corruption primitive, no privilege escalation path, no sensitive data exposure, and no runtime unprivileged trigger. Theoretical impact is boot delay or boot-time DoS, while realistic exploitation evidence is limited to affected virtual boot configurations. ## 5. One-sentence report phrase The jiffies clocksource may be used before registration during early boot, causing time reads to be clamped and producing a long boot delay or boot-time denial of service on affected Xen HVM guests. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can be auto-closed for security triage because it is a boot-time initialization bug with no memory corruption, no network reachability, no privilege escalation evidence, and only availability impact in a specific virtualized boot scenario. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: time/jiffies: Register jiffies clocksource before usage [ Upstream Commit: fe9bdea65ba231fcfb155031628bb1e8491b5fe0 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fe9bdea65ba231fcfb155031628bb1e8491b5fe0 Changed files: kernel/time/jiffies.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=fe9bdea65ba231fcfb155031628bb1e8491b5fe0 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68092 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68092 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: 0 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).