From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-64078][LOW] netfilter: x_tables: add and use xtables_unregister_table_exit [ Upstream Date: Sun, 19 Jul 2026 12:20:54 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-64078 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: 3 X-AL-KERNEL-ActionableScore-Lower: 0 X-AL-KERNEL-Commit: 86ee5bc9c0f0e652e19f395675a432de11b75514 List-Id: CVE: CVE-2026-64078 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: netfilter: x_tables: add and use xtables_unregister_table_exit [ Upstream Commit: 86ee5bc9c0f0e652e19f395675a432de11b75514 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=86ee5bc9c0f0e652e19f395675a432de11b75514 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64078 Analysis date: Sun, 19 Jul 2026 12:20:54 -0400 ActionableScore: 3 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like, not an Important candidate Manual review required: NO Summary: x_tables could fail to complete table unregister cleanup after pre_exit removed a table from the active list, causing leaked table resources during netns teardown or rmmod and allowing only local resource exhaustion in plausible cases. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64078 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64078 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-2026-64078 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-401;*CWE-772;*CWE-664;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'x_tables table cleanup could be incomplete during network namespace teardown or rmmod because the pre_exit stage removed the table from the active list before the exit stage tried to find and free it. This can leave xt table resources and related per family data behind and may cause resource leakage or cleanup failures after repeated namespace or module lifecycle operations. For the CVSS the PR:L is used for the paranoid score because an untrusted local user may be able to create a user and network namespace and gain CAP_NET_ADMIN inside that namespace on systems where unprivileged user namespaces are enabled. The issue is not directly network reachable and is triggered by local control plane lifecycle operations rather than packet traffic. Impact is denial of service through resource exhaustion only, with no supported confidentiality or integrity impact from the patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like, not an Important candidate (with actual score 2) SKIP CVE-2026-64078 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: fdacd57c79b79a03c7ca88f706ad9fb7b46831c1 YES NO NO unknown MAYBE OOB LOCK DISK INIT NETFILTER LOG HARDWARE IPV6 PACKET DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 3 * Final recommended bucket: **Ordinary Moderate / Low-like, not an Important candidate**:: ## 2. Signal breakdown Conservative signals: * Requires admin/root/CAP_NET_ADMIN or module lifecycle control in typical deployments: -2 The realistic trigger is netns teardown, x_tables table unregister, or rmmod/module exit behavior, normally controlled by privileged code. * Availability impact realistic: +1 The failure mode is incomplete cleanup and possible resource leakage after repeated lifecycle operations. * Broad/default/common subsystem: +1 netfilter x_tables is a common kernel subsystem, but this bug is in unregister/teardown control plane rather than packet processing. Conservative total: 0. Paranoid additional signals: * Local unprivileged trigger: +1 On systems with unprivileged user namespaces enabled, a local user may create a user/net namespace and obtain CAP_NET_ADMIN inside that namespace, making repeated namespace lifecycle triggering more plausible. * Availability impact realistic: +1 Repeated teardown could leak kernel resources and eventually affect availability. * Broad/default/common subsystem: +1 x_tables/netfilter remains common enough to avoid treating this as rare-only exposure. Paranoid total: 3. Not awarded: * No generic memory corruption signal. The patch shows missing second-stage cleanup, not UAF, OOB write, double free, type confusion, or arbitrary write. * No privilege escalation signal. No credible LPE primitive is visible. * No confidentiality or integrity signal. The issue is cleanup/resource lifetime only. * No remote/network-triggerable signal. Packet traffic does not trigger the vulnerable path. ## 3. Reachability analysis Typical reachability is local privileged: CAP_NET_ADMIN in the relevant namespace for netfilter table operations, or stronger privileges for rmmod/module lifecycle. The bug is not triggered by packet processing and is not remotely reachable over the network. Namespaces matter. In products where unprivileged user namespaces are enabled, a local unprivileged user may be able to create a net namespace and trigger x_tables setup and teardown paths with namespace-local CAP_NET_ADMIN. That supports the paranoid local-unprivileged interpretation, but still only for resource leakage/DoS, not memory corruption or LPE. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like resource cleanup issue. It is worth tracking and fixing, but it is not an Important-class candidate from the provided patch context. The theoretical worst case is resource exhaustion after repeated namespace or module lifecycle operations. Realistic exploitation evidence is limited to incomplete cleanup and leaks. There is no demonstrated stale-object reuse, write-after-free, callback corruption, arbitrary write, or security-boundary bypass. ## 5. One-sentence report phrase x_tables could fail to complete table unregister cleanup after pre_exit removed a table from the active list, causing leaked table resources during netns teardown or rmmod and allowing only local resource exhaustion in plausible cases. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can be auto-closed for urgent security triage because the patch supports a resource leak / lifecycle cleanup classification only, with no memory corruption, no remote trigger, no confidentiality or integrity impact, and no plausible privilege escalation primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: netfilter: x_tables: add and use xtables_unregister_table_exit [ Upstream Commit: 86ee5bc9c0f0e652e19f395675a432de11b75514 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=86ee5bc9c0f0e652e19f395675a432de11b75514 Changed files: include/linux/netfilter/x_tables.h net/ipv4/netfilter/arp_tables.c net/ipv4/netfilter/ip_tables.c net/ipv4/netfilter/iptable_nat.c net/ipv6/netfilter/ip6_tables.c net/ipv6/netfilter/ip6table_nat.c net/netfilter/x_tables.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=86ee5bc9c0f0e652e19f395675a432de11b75514 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64078 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64078 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: 3 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).