From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-45901][LOW] netfilter: nf_tables: revert commit_mutex usage in reset path [ Upstream Date: Wed, 27 May 2026 22:21:22 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-45901 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: 1 X-AL-KERNEL-Commit: ee3978b6a0dcd4215cb7cedcba705a12174786a7 List-Id: CVE: CVE-2026-45901 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: netfilter: nf_tables: revert commit_mutex usage in reset path [ Upstream Commit: ee3978b6a0dcd4215cb7cedcba705a12174786a7 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ee3978b6a0dcd4215cb7cedcba705a12174786a7 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45901 Analysis date: Wed, 27 May 2026 22:21:22 -0400 ActionableScore: 3 ActionableScore lower bound: 1 Actionable bucket: Borderline, manual review recommended Manual review required: YES Summary: A nf_tables reset locking bug can deadlock with ipset and netlink callback locks during concurrent firewall control-plane operations, causing local firewall management DoS. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45901 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45901 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: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-45901 LOW CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-667;*CWE-833;**CWE-400;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'nf_tables reset operations could take commit_mutex in paths that interact with ipset and netlink dump callbacks, creating a circular lock dependency between commit_mutex, nfnl_subsys_ipset, and nlk_cb_mutex. A local actor with nftables and ipset configuration rights could trigger a deadlock by running nft reset, ipset list, and iptables-nft set matching operations concurrently. For the CVSS the PR:L is used in the paranoid score because delegated CAP_NET_ADMIN in containers or service accounts can expose these control plane operations below full host root, while typical host triggering requires network administration privileges. The issue is not network reachable and is triggered through netfilter configuration operations rather than packet traffic. Impact is denial of service through stuck netfilter or netlink control plane operations. No supported evidence indicates information disclosure, integrity impact, kernel memory corruption, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 2) MAYBE REMOTE LOCK DANGER INIT NETFILTER SKB LOG LINUS SYZBOT 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=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 3 * Final recommended bucket: **Borderline, manual review recommended**:: ## 2. Signal breakdown * Reliable kernel/control-plane DoS: +1 The bug can create a circular lock dependency and deadlock nf_tables/ipset/netlink control-plane operations. * Availability impact realistic: +1 A deadlock can leave nftables reset, ipset list, or iptables-nft operations stuck, affecting firewall management. * Broad/common subsystem: +1 in paranoid scoring nf_tables, ipset compatibility, and iptables-nft are common firewall/control-plane components. * Local delegated network administration trigger: +1 in paranoid scoring In containers, namespaces, appliances, or managed services, CAP_NET_ADMIN-like firewall control may be delegated below full host root. * Requires CAP_NET_ADMIN in typical deployments: -2 conservative Normal triggering requires nftables/ipset/iptables-nft configuration rights. * Concurrent/special operation mix required: -1 The issue requires overlapping nft reset, ipset list, and iptables-nft set matching operations. * No memory corruption: +0 This is a locking/order bug, not UAF, OOB write, arbitrary write, or object lifetime corruption. * No direct network reachability: +0 The trigger is local netfilter configuration activity, not packet traffic. ## 3. Reachability analysis A local actor with nftables and ipset administration rights can trigger the issue by running the affected reset and listing operations concurrently with iptables-nft set matching. In normal host deployments this requires CAP_NET_ADMIN. Namespaces and containers can lower the practical barrier if network administration is delegated to tenants or service accounts. The issue is not remotely packet-triggerable. Traffic may exist in the environment, but the vulnerable path is netlink/control-plane locking. ## 4. Severity interpretation This behaves like ordinary Moderate or borderline Moderate availability impact. It is operationally relevant because nf_tables is common and firewall management may hang, but it is not memory corruption, not privilege escalation, and not a remote network parsing flaw. The paranoid score is higher only for deployments that delegate firewall administration to less trusted users. ## 5. One-sentence report phrase A nf_tables reset locking bug can deadlock with ipset and netlink callback locks during concurrent firewall control-plane operations, causing local firewall management DoS. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED No manual check is needed for standard deployments where nftables and ipset management requires trusted CAP_NET_ADMIN. Review only if delegated firewall administration is exposed to untrusted tenants or service accounts. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: netfilter: nf_tables: revert commit_mutex usage in reset path [ Upstream Commit: ee3978b6a0dcd4215cb7cedcba705a12174786a7 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ee3978b6a0dcd4215cb7cedcba705a12174786a7 Changed files: net/netfilter/nf_tables_api.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=ee3978b6a0dcd4215cb7cedcba705a12174786a7 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45901 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45901 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:H/PR:H/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.7 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: 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).