From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98408][LOW] watchdog: rzv2h: Avoid division by zero Date: Wed, 14 Oct 2026 22:52:04 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98408 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: eb14ee406e1d0fbbfb857f0eaa710daa8c2dc30e List-Id: CVE: CVE-2026-98408 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: watchdog: rzv2h: Avoid division by zero Commit: eb14ee406e1d0fbbfb857f0eaa710daa8c2dc30e Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eb14ee406e1d0fbbfb857f0eaa710daa8c2dc30e Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98408 Analysis date: Wed, 14 Oct 2026 22:52:04 -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-2026-98408 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98408 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-2026-98408 LOW https://www.kernelcve.org/list/?q=CVE-2026-98408 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=LOW RESULT=DIFF TEMP_DISTANCE_MERGE_SKIP=AEGIS_LOW_ELIGIBLE_NO_POSITIVE_SIGNAL (independent Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE_KPANIC) 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-369;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: '4.4';DESCR 'The RZ V2H watchdog driver can divide by zero during rzv2h_wdt_probe when clk_get_rate() returns zero for the watchdog count clock. This can cause a kernel panic while the driver is being initialized and may prevent the affected system from completing device initialization or booting normally. For the CVSS the PR:H value is used because reliable triggering normally requires administrative control over the device configuration, firmware, device tree, clock provider, or driver reprobe operation. The issue is not network reachable and is limited to systems with the affected watchdog hardware and a zero clock rate condition. The demonstrated impact is denial of service only. No memory corruption primitive, information disclosure, or privilege escalation path is supported by the affected calculation. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.4 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3. The independent weaker Aegis shadow evaluated CVSS 4.2 and ActionableScore 0 with primitive class CLASS_C and manual review NO. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE DANGER SIMPLEFIX ERRORPATH HARDWARE LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 1 * Paranoid score: 1 * No floor or cap was applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Reliable kernel crash / strong DoS. A zero return from `clk_get_rate()` is used directly as a divisor during `rzv2h_wdt_probe()`, causing a division-by-zero panic. * No additional Availability point. It would double-count the same panic. * No corruption point. The operation is an integer division with a zero divisor, not an OOB access, UAF, stale-object use, or memory overwrite. * No authorization or security-boundary point. No access-control decision changes from DENY to ALLOW. * No reachability bonus. No remote or ordinary-user interface for forcing the clock rate to zero is established. * No host-admin penalty. Administrative control is plausible for deliberate reconfiguration or reprobe, but the supplied evidence does not positively establish a complete attacker-controlled trigger. * No rare-hardware penalty. RZ/V2H hardware is required, but the evidence does not establish the stronger rare or physical-attacker condition required for the deduction. * NEW52 B5-R does not apply. There is no heap OOB write, retry-accumulated offset, or later consumption of corrupted structured state. * NEW53 B3-PENDING does not apply. There is no shared-backing write. * NEW54 B4-PENDING does not apply. There is no authorization guard or protected resource involved. 3. Reachability analysis The fault occurs during platform-driver probe when the watchdog count clock reports a zero rate. It may arise from firmware, device-tree, clock-provider, hardware, or initialization state, but no attacker-invocable runtime operation that reliably forces this condition is shown. An administrator may be able to influence device configuration or reprobe behavior, but this is not enough to positively establish that host-admin powers are required for every occurrence. Therefore `HostAdminRequired=UNKNOWN` and `RequiresHostUID0=UNKNOWN`. The platform-device probe path is not namespace-scoped. There is no network trigger, ordinary-user trigger, namespace capability path, or repeatable race. Compatible RZ/V2H hardware and the affected driver are prerequisites. 4. Primitive and severity interpretation The exact primitive is division by zero during calculation of `max_hw_heartbeat_ms`. The demonstrated consequence is a kernel panic during watchdog initialization, potentially disrupting device initialization or boot. There is no stale storage, active structured UAF, repeated release, refcount mutation, OOB write, shared-page modification, or authorization bypass. The bug is therefore `CLASS_C`, representing crash-only invalid-state behavior. No meaningful exploitation leverage remains after excluding the panic. Privilege escalation, confidentiality impact, integrity impact, and persistent corruption are unsupported. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` because no unresolved corruption or security-boundary primitive exists. 5. One-sentence report phrase A zero watchdog count clock rate causes a division-by-zero panic during RZ/V2H watchdog probe, with no demonstrated memory-corruption, authorization-bypass, or attacker-reachable exploitation primitive. 6. Manual review recommendation NO MANUAL CHECK NEEDED The patch addresses a hardware-specific input-validation failure with a crash-only consequence and no established security primitive beyond availability loss. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: watchdog: rzv2h: Avoid division by zero Commit: eb14ee406e1d0fbbfb857f0eaa710daa8c2dc30e Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eb14ee406e1d0fbbfb857f0eaa710daa8c2dc30e Commit description: clk_get_rate() could return 0. Avoid a division by zero panic. Fixes: f6febd0 ("watchdog: Add Watchdog Timer driver for RZ/V2H(P)") Cc: stable@vger.kernel.org Signed-off-by: Tzung-Bi Shih Link: https://patch.msgid.link/20260913064851.8239-4-tzungbi@kernel.org Signed-off-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman Changed files: drivers/watchdog/rzv2h_wdt.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=eb14ee406e1d0fbbfb857f0eaa710daa8c2dc30e ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98408 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98408 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: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: 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).