From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97956][LOW] net: net_failover: Fix the deadlock in net_failover_slave_name_change() [ Upstream Date: Fri, 25 Sep 2026 08:35:42 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97956 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: 4b20e66d2e52d3628db4dccc1a33f134e73375d5 List-Id: CVE: CVE-2026-97956 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: net: net_failover: Fix the deadlock in net_failover_slave_name_change() [ Upstream Commit: 4b20e66d2e52d3628db4dccc1a33f134e73375d5 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4b20e66d2e52d3628db4dccc1a33f134e73375d5 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97956 Analysis date: Fri, 25 Sep 2026 08:35:42 -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-2026-97956 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97956 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-2026-97956 LOW https://www.kernelcve.org/list/?q=CVE-2026-97956 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:L/UI:N/S:U/C:N/I:N/A:H';*CWE-833;CWE-667;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'A locking error in net_failover_slave_name_change can call dev_open while an upper rtnetlink path already holds the network device instance lock. The recursive lock acquisition can block indefinitely during a failover slave rename and can stall network device management operations. For the CVSS the PR:L value is used because a local process generally needs CAP_NET_ADMIN or delegated network administration rights to rename the affected interface. The issue is not directly network reachable through packet traffic and requires a configured net_failover device with a rename event. Impact is denial of service through a deadlocked control path. No memory corruption or privilege escalation primitive is present in the analyzed path.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) SKIP CVE-2026-97956 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES NO NO unknown MAYBE DEADLOCK NETWORK DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - 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 * No floor or cap applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Reliable strong DoS. Recursive acquisition of the network-device instance lock can block indefinitely and stall rtnetlink network-device management. * No additional Availability point. The stalled control path is the same deadlock consequence. * No memory-corruption signal. The patch establishes lock recursion, not UAF, OOB access, stale-object use, or overwrite. * No remote-reachability point. Network packets do not directly reach this path. * No local-unprivileged point. The rename operation requires network-administration authority. * No privilege penalty. CAP_NET_ADMIN is implicated, but the supplied evidence does not establish whether the complete operation requires host-equivalent authority or works with delegated namespace authority. * No race penalty. This is a deterministic nested-lock sequence rather than a narrow timing race. * No repeated release or refcount operation exists. * No confidentiality, integrity, LPE, controlled-reclaim, or arbitrary-write signal is established. 3. Reachability analysis The trigger is a local rtnetlink setlink operation that renames a slave belonging to an existing net_failover configuration. The caller normally needs CAP_NET_ADMIN governing the affected device, but the supplied context does not resolve the relevant user namespace or prove that the complete trigger works in an attacker-created network namespace. A configured net_failover device and slave rename event are prerequisites. The input does not establish whether an attacker can instantiate the required topology without prior privileged setup. No special physical hardware requirement is established. Triggering is not race-dependent and should be deterministic once the required device state and permissions exist. 4. Primitive and severity interpretation The exact primitive is recursive mutex acquisition. An upper rtnetlink caller already holds the netdev instance lock, after which `net_failover_slave_name_change()` calls `dev_open()` and attempts to acquire that lock again. This is CLASS_C because the demonstrated behavior is an indefinite deadlock and control-plane DoS without a separate corruption or lifetime primitive. There is no stale storage, active-object UAF, repeated lifetime mutation, authorization bypass, or leverage beyond blocking network-device management. ImportantCandidate is NO because no Important-preserving primitive is present. AutoDowngradeAllowed is YES because the issue is limited to a local, permission-gated deadlock with no unresolved memory-corruption or security-boundary mechanism. Operational severity is ordinary Moderate or Low-like depending on how broadly the held locks affect network administration. 5. One-sentence report phrase A local network administrator can trigger a recursive netdev lock acquisition while renaming a net_failover slave, indefinitely stalling the affected rtnetlink control path without causing memory corruption or privilege escalation. 6. Manual review recommendation NO MANUAL CHECK NEEDED The patch and stack trace establish a straightforward lock-recursion DoS, with no unresolved corruption, lifetime, authorization, or remote-exposure primitive. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net: net_failover: Fix the deadlock in net_failover_slave_name_change() [ Upstream Commit: 4b20e66d2e52d3628db4dccc1a33f134e73375d5 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4b20e66d2e52d3628db4dccc1a33f134e73375d5 Changed files: drivers/net/net_failover.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=4b20e66d2e52d3628db4dccc1a33f134e73375d5 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97956 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97956 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:L/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: 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).