From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97480][LOW] tty: serial: 8250: protect against NULL uart->port.dev in register [ Upstream Date: Thu, 24 Sep 2026 17:34:51 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97480 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: 5cbab666721d974bfe033a12045d808936deaefd List-Id: CVE: CVE-2026-97480 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: tty: serial: 8250: protect against NULL uart->port.dev in register [ Upstream Commit: 5cbab666721d974bfe033a12045d808936deaefd Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5cbab666721d974bfe033a12045d808936deaefd Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97480 Analysis date: Thu, 24 Sep 2026 17:34:51 -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-2026-97480 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97480 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-2026-97480 LOW https://www.kernelcve.org/list/?q=CVE-2026-97480 CHECK WITH IMPACT FROM ORIG NN MODERATE 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-476;BEST CVSS score: '4.4';DESCR 'A NULL pointer dereference can occur in serial8250_register_8250_port when both the existing UART slot and the supplied UART port have no parent device. The code passes a NULL uart port dev pointer to has_acpi_companion which dereferences the device pointer while checking the ACPI companion. This can cause a kernel Oops or panic during legacy non OF non ACPI serial port registration. For the CVSS the PR:H because reaching this registration path typically requires administrative control over driver loading device registration or platform configuration. The issue is not network reachable. Impact is denial of service only. The patch context does not show a use after free out of bounds access information leak or write primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) YES PRINTF-TTY HARDWARE LINUS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 1 * Paranoid score: 1 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap was applied. 2. Signal breakdown * +1 Reliable kernel crash or strong DoS. A NULL `uart->port.dev` is passed to `has_acpi_companion()`, which dereferences `dev->fwnode`. This can generate a kernel Oops and may panic systems configured to panic on Oops. * No remote reachability awarded. The vulnerable operation is an internal serial-port registration path, not packet processing or a remotely exposed protocol handler. * No local unprivileged trigger awarded. The supplied patch does not establish that an ordinary local user can cause a legacy no-device 8250 port registration. * No host-admin penalty applied. Host-admin-equivalent privilege is plausible for driver or platform registration, but it is not positively established by the supplied call-path evidence. * No memory-corruption signal awarded. This is a direct NULL dereference, not a UAF, double free, OOB access, refcount mutation, or write primitive. * No confidentiality or integrity signal awarded. No disclosure, unauthorized modification, or security-boundary bypass is established. * No special race penalty applied. The defect is an ordered invalid-state condition, not a timing race. 3. Reachability analysis The vulnerable function is reached when a kernel driver or legacy platform-registration caller invokes `serial8250_register_8250_port()` with no parent device and the selected existing UART slot also has no device pointer. The supplied context identifies legitimate legacy non-OF and non-ACPI callers, but does not identify a userspace interface through which an ordinary unprivileged user can create such a registration. Administrative driver loading, platform-device setup, boot-time configuration, or an in-kernel caller may be required in practical deployments, but the complete privilege boundary is not visible. Therefore `HostAdminRequired=UNKNOWN`, not `YES`. No namespace-specific capability checks or complete namespace-reachable trigger path are shown, so `NamespaceScopedPrivilege=UNKNOWN`. No special hardware is proven necessary beyond the presence of a relevant legacy serial registration path. No remote input, firmware-controlled input, or attacker-controlled serial data path reaches the faulty check. 4. Primitive and severity interpretation The exact primitive is a NULL-pointer dereference in `has_acpi_companion(uart->port.dev)` when `uart->port.dev` remains NULL after conditional initialization. This is an invalid-state crash primitive, classified as `CLASS_C`. There is no freed object, stale post-lifetime reference, RCU lifetime mismatch, repeated release, refcount mutation, active-object reuse, controlled replacement, callback consumption, arbitrary write, or information-disclosure path. The demonstrated consequence is kernel Oops or possible panic, which is a denial of service. Privilege escalation and confidentiality or integrity impact are speculative and unsupported by this patch. `ImportantCandidate=NO` because there is no meaningful unresolved corruption or boundary-bypass primitive beyond the crash. `AutoDowngradeAllowed=YES` because the issue is a constrained NULL dereference with no demonstrated attacker-controlled memory-corruption leverage. 5. One-sentence report phrase A NULL pointer dereference in serial8250_register_8250_port can crash the kernel when a legacy serial port registration has no parent device, but no memory-corruption or privilege-escalation primitive is established. 6. Manual review recommendation NO MANUAL CHECK NEEDED The patch fixes a direct NULL dereference in a legacy registration path. The supplied evidence establishes only crash-level impact and does not show unprivileged reachability, remote reachability, memory corruption, or a security-boundary bypass. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: tty: serial: 8250: protect against NULL uart->port.dev in register [ Upstream Commit: 5cbab666721d974bfe033a12045d808936deaefd Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5cbab666721d974bfe033a12045d808936deaefd Changed files: drivers/tty/serial/8250/8250_core.c:767 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=5cbab666721d974bfe033a12045d808936deaefd ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97480 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97480 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: Not available 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).