From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-53001][LOW] netfilter: xtables: restrict several matches to inet family [ Upstream Date: Thu, 25 Jun 2026 11:18:25 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-53001 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: 1 X-AL-KERNEL-Commit: 14203f9edf944b3fb63faadd62f38452421ecdfc List-Id: CVE: CVE-2026-53001 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: netfilter: xtables: restrict several matches to inet family [ Upstream Commit: 14203f9edf944b3fb63faadd62f38452421ecdfc Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=14203f9edf944b3fb63faadd62f38452421ecdfc Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53001 Analysis date: Thu, 25 Jun 2026 11:18:25 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: Several xtables matches were registered for unsupported protocol families, which could allow invalid firewall rules and cause limited filtering policy mismatch, but triggering requires rule-management privileges and no memory corruption or crash primitive is evident. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53001 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53001 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-2026-53001 LOW CHECK 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:L/A:N';CWE-693;CWE-284;CWE-670;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N';BEST CVSS score: '3.3';DESCR 'Several xtables matches were registered for NFPROTO_UNSPEC even though their logic is only valid for IPv4 and IPv6, or only IPv4 for realm. This can allow rules to be accepted in unsupported protocol families and may create a filtering policy mismatch rather than a memory corruption primitive. For the CVSS the PR:L value is used for the paranoid score because delegated CAP_NET_ADMIN, container root, or firewall management service accounts may be able to install netfilter rules without being full host root. The issue is not directly network reachable because triggering requires control plane rule configuration, while packet traffic only exercises rules after they have been installed. Impact is limited integrity impact from possible firewall policy bypass or incorrect filtering behavior. No credible confidentiality impact, privilege escalation primitive, or kernel crash is indicated by the patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) MAYBE REMOTE INIT NETFILTER IPV6 DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like** ## 2. Signal breakdown Conservative signals: * Integrity impact plausible: +1 Unsupported xtables matches may allow rules to be accepted in protocol families where their semantics are not valid, causing filtering policy mismatch. * Common netfilter control-plane exposure: +1 The affected code is in netfilter xtables registration and rule validation context. * Requires CAP_NET_ADMIN in typical deployments: -2 Installing or modifying xtables rules normally requires administrative network privileges. Conservative total: 1 Paranoid adjustment: * Cross-boundary or policy bypass concern: +1 In delegated CAP_NET_ADMIN, container root, or firewall management service scenarios, incorrect rule acceptance may weaken an intended filtering boundary. * Do not apply the full -2 privilege penalty in this reduced-capability scenario. This raises the practical paranoid score to 2, but still does not make it actionable enough for Important handling. ## 3. Reachability analysis The bug is triggered through netfilter rule configuration, not by ordinary packet traffic alone. A remote attacker cannot directly trigger the vulnerable condition unless they already control a firewall management plane. In typical host deployments, CAP_NET_ADMIN is required, so this is not reachable by an unprivileged local user. Namespaces or containers can lower the practical privilege requirement if CAP_NET_ADMIN is delegated, but the issue still remains a control-plane policy correctness bug rather than memory corruption. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like issue. The patch does not show UAF, OOB access, type confusion, NULL dereference, kernel crash, or privilege escalation. The realistic impact is limited integrity impact from possible firewall policy mismatch or incorrect rule placement in unsupported protocol families. The paranoid interpretation keeps it visible as a policy bypass concern in delegated administration environments, but not as an Important candidate. ## 5. One-sentence report phrase Several xtables matches were registered for unsupported protocol families, which could allow invalid firewall rules and cause limited filtering policy mismatch, but triggering requires rule-management privileges and no memory corruption or crash primitive is evident. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED Reason: no memory corruption, no remote trigger, no crash primitive, and typical exploitation requires CAP_NET_ADMIN with only limited integrity policy impact. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: netfilter: xtables: restrict several matches to inet family [ Upstream Commit: 14203f9edf944b3fb63faadd62f38452421ecdfc Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=14203f9edf944b3fb63faadd62f38452421ecdfc Changed files: net/netfilter/xt_mac.c net/netfilter/xt_owner.c net/netfilter/xt_physdev.c net/netfilter/xt_realm.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=14203f9edf944b3fb63faadd62f38452421ecdfc ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53001 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53001 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:L/A:N The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N The Best / paranoid CVSS score: 3.3 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: 1 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).