From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98903][LOW] mailbox: imx: Add a channel shutdown field [ Upstream Date: Mon, 26 Oct 2026 15:00:29 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98903 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: 02273054b2e94e53065ea5644265bb9d8f7ee2a7 List-Id: CVE: CVE-2026-98903 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: mailbox: imx: Add a channel shutdown field [ Upstream Commit: 02273054b2e94e53065ea5644265bb9d8f7ee2a7 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=02273054b2e94e53065ea5644265bb9d8f7ee2a7 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98903 Analysis date: Mon, 26 Oct 2026 15:00:29 -0400 ActionableScore: 0 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A narrow i.MX mailbox teardown race can re-enable a removed channel’s interrupt and cause irq-core to disable a shared IRQ, resulting in availability loss without demonstrated memory corruption. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98903 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98903 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-2026-98903 LOW https://www.kernelcve.org/list/?q=CVE-2026-98903 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=0 LEGACY=LOW RESULT=SAME (final reconciliation agrees; DECISION: both LOW) 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:N/A:H';CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A teardown race in the i.MX mailbox driver allows an active ISR to re enable a channel event after imx_mu_shutdown has disabled it and while free_irq is waiting for the handler. A removed mailbox channel can then continue generating interrupts and the irq core may disable a shared interrupt line with a nobody cared condition, causing availability loss for the mailbox and potentially other devices sharing that IRQ. For the CVSS the PR:H base value reflects that channel teardown normally requires privileged kernel device management rather than ordinary local access. For the CVSS the PR:L paranoid value covers deployments where a less privileged service or remote processor can influence mailbox events and channel lifecycle, but the required race makes AC:H and there is no demonstrated memory corruption primitive. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. No severity changing production threshold or specialist override was recorded. 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. The independent weaker Aegis shadow evaluated CVSS 2.0 and ActionableScore 0 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) MAYBE LOCK INIT RACE HARDWARE LINUS - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 0 (+1 availability impact, -1 narrow teardown race). * Conservative score: 0. No floor or cap applied. * Raw paranoid score: 0; no stronger patch-supported primitive exists. * Paranoid score: 0. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Reliable strong DoS: if the race occurs, the ISR re-enables the removed channel’s event and irq-core may disable the shared interrupt with “nobody cared,” potentially disrupting the mailbox and other devices sharing that IRQ. * -1 Hard timing requirement: shutdown must disable the event while the ISR is active, followed by ISR re-enablement before `free_irq()` completes. * No memory corruption, UAF, OOB access, repeated lifetime mutation, disclosure, authorization bypass, or attacker-controlled write is shown. * No extra availability point: shared-IRQ disruption is the same consequence already counted. * No B5-R retry-accumulated OOB or B3 shared-backing write mechanics exist. 3. Reachability analysis The patch establishes a race between mailbox-channel shutdown and an active hardware ISR. It does not establish which userspace actor can request channel teardown, whether an ordinary user or delegated service can control both lifecycle and mailbox events, or whether any relevant capability is namespace-scoped. The legacy summary’s statement that teardown “normally” requires privileged device management is insufficient to prove host-admin-only triggering. i.MX MU hardware and a shared IRQ are required; the hardware is platform-specific, but not proven rare enough for another penalty. 4. Primitive and severity reading The exact defect is synchronization failure over active interrupt-enable state: teardown clears the event, but an in-flight ISR can restore it. This is CLASS_C availability behavior, not a stale-memory or structured-corruption primitive. The shown consequence is IRQ shutdown and device/service disruption; kernel panic, host memory corruption, and cross-boundary integrity effects are unproven. ImportantCandidate is therefore NO, and automatic Moderate downgrade is allowed. 5. One-sentence report phrase A narrow i.MX mailbox teardown race can re-enable a removed channel’s interrupt and cause irq-core to disable a shared IRQ, resulting in availability loss without demonstrated memory corruption. 6. Manual review advice NO MANUAL CHECK NEEDED The patch supports a timing-dependent availability defect with no unresolved corruption or authorization primitive. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: mailbox: imx: Add a channel shutdown field [ Upstream Commit: 02273054b2e94e53065ea5644265bb9d8f7ee2a7 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=02273054b2e94e53065ea5644265bb9d8f7ee2a7 Changed files: drivers/mailbox/imx-mailbox.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=02273054b2e94e53065ea5644265bb9d8f7ee2a7 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98903 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98903 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:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.7 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).