From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-63997][LOW] ethtool: module: avoid leaking a netdev ref on module flash errors [ Upstream Date: Sun, 19 Jul 2026 20:28:24 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-63997 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: 2 X-AL-KERNEL-ActionableScore-Lower: 0 X-AL-KERNEL-Commit: f7b4513e77f9571dc1041a798b93b5c4a4bfc191 List-Id: CVE: CVE-2026-63997 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: ethtool: module: avoid leaking a netdev ref on module flash errors [ Upstream Commit: f7b4513e77f9571dc1041a798b93b5c4a4bfc191 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f7b4513e77f9571dc1041a798b93b5c4a4bfc191 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63997 Analysis date: Sun, 19 Jul 2026 20:28:24 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: An ethtool module firmware flash error path can leak a netdev reference and leave the flash state marked in progress, causing local device-management denial of service, but exploitation normally requires privileged network-device control and does not show memory corruption. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-63997 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63997 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-2026-63997 LOW CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-772;CWE-404;**CWE-400;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'A resource leak in ethtool module firmware flashing can occur when module_flash_fw_schedule hits an error after marking module_fw_flash_in_progress and taking a netdev reference but before the flash work is actually scheduled. This can leave the network device reference held and keep the flash operation state stuck, which may block later flash attempts or interfere with device teardown. For the CVSS the PR:L is used in the paranoid score because some environments delegate CAP_NET_ADMIN or network device management to a reduced capability service or container root, while the typical base case is administrator controlled. The issue is local control plane only and is not network reachable through packet traffic. Impact is denial of service through resource leakage or stuck device state, with no evidence of memory corruption or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) YES SIMPLEFIX LEAK HARDWARE LINUS INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown Triggered signals: * Reliable resource leak / stuck device state: +1 The error path can leave a netdev reference held and module_fw_flash_in_progress set, blocking later module flash operations or interfering with device teardown. * Availability impact realistic: +1 The impact is persistent local device-management degradation rather than a one-shot warning. It may require cleanup, driver reload, device removal handling, or reboot in bad cases. * Requires admin/root/CAP_NET_ADMIN in typical deployments: -2 conservative only Transceiver module firmware flashing through ethtool is normally a privileged network-device management operation. Not triggered: * Remote reachable: +0 This is not packet-triggered and not reachable over the network data path. * Local unprivileged trigger: +0 No evidence that an unprivileged user can trigger the firmware flash operation in typical deployments. * Memory corruption / UAF / double free / OOB: +0 The patch fixes ordering of flag setting and netdev_hold. It does not show stale dereference, UAF, overwrite, object confusion, or arbitrary memory access. * Privilege escalation plausible: +0 No LPE primitive is visible. The issue is a reference leak and stuck state. Call-site confidence: high. The relevant function and affected error path are present in the patch. ## 3. Reachability analysis The bug is triggered through the ethtool module firmware flashing control path. In normal deployments this requires administrative network-management privileges such as CAP_NET_ADMIN or equivalent service-level access. Namespaces or delegated container/service models may reduce the practical privilege barrier, which is why the paranoid score does not apply the full admin penalty. The path is not default packet-processing behavior and is only relevant on systems with supported transceiver module firmware flashing. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like resource-management issue, not an Important-class vulnerability. The realistic impact is denial of service against device-management state, possible blocked follow-up flash operations, or netdev teardown complications. There is no concrete memory corruption, confidentiality impact, integrity impact, or privilege-escalation path supported by the patch. ## 5. One-sentence report phrase An ethtool module firmware flash error path can leak a netdev reference and leave the flash state marked in progress, causing local device-management denial of service, but exploitation normally requires privileged network-device control and does not show memory corruption. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can be auto-closed for security triage unless the target product delegates ethtool firmware flashing to untrusted service accounts or containers. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ethtool: module: avoid leaking a netdev ref on module flash errors [ Upstream Commit: f7b4513e77f9571dc1041a798b93b5c4a4bfc191 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f7b4513e77f9571dc1041a798b93b5c4a4bfc191 Changed files: net/ethtool/module.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=f7b4513e77f9571dc1041a798b93b5c4a4bfc191 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-63997 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63997 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:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 5.5 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: 2 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).