From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-63914][MODERATE 7.0] xfrm: route MIGRATE notifications to caller's netns Date: Sun, 19 Jul 2026 17:41:51 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-63914 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 5 X-AL-KERNEL-ActionableScore-Lower: 4 X-AL-KERNEL-Commit: bafc7d0774b9bf52909c70ed990bc5ccf7ec4bad List-Id: CVE: CVE-2026-63914 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: xfrm: route MIGRATE notifications to caller's netns Commit: bafc7d0774b9bf52909c70ed990bc5ccf7ec4bad Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bafc7d0774b9bf52909c70ed990bc5ccf7ec4bad Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63914 Analysis date: Sun, 19 Jul 2026 17:41:51 -0400 ActionableScore: 5 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: XFRM MIGRATE notifications were incorrectly multicast in init_net instead of the caller network namespace, exposing IPsec migration metadata across namespace boundaries and breaking per-netns IKE migration handling. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-63914 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63914 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: MODERATE 7.0 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-2026-63914 MODERATE 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:L/I:L/A:L';CWE-668;*CWE-200;CWE-284;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '5.3';DESCR 'XFRM MIGRATE notifications were multicast in init_net even when the migration request originated from a different network namespace. This can expose IPsec migration metadata such as selectors, old and new endpoint addresses, and km_address to listeners in init_net, while the IKE daemon inside the originating namespace may miss its own migration event. For the CVSS the PR:L is used in the paranoid score because a reduced capability container root or delegated service account with CAP_NET_ADMIN in its own network namespace may be able to trigger the affected control plane path. The issue is not directly network reachable and is not a memory corruption bug. Impact is mainly namespace isolation bypass, limited confidentiality exposure, possible limited integrity confusion in user space IKE handling, and availability impact for MOBIKE or address update handling inside non init namespaces.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5) YES REMOTE DANGER INIT SKB LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH KPANIC INCREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN5 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=4 ## 1. ActionableScore * Conservative score: 4 * Paranoid score: 5 * Final recommended bucket: **Actionable Moderate at minimum**:: ## 2. Signal breakdown * Security-boundary bypass with practical sensitive-object access: +2 MIGRATE notifications from a non-init network namespace are delivered to init_net listeners, violating netns isolation and exposing IPsec/XFRM migration metadata. * Cross-boundary isolation/policy bypass: +1 The bug crosses a network namespace boundary and breaks the expected per-netns XFRM/PF_KEY notification model. * Confidentiality impact plausible: +1 Selectors, old/new endpoint addresses, and km_address can be disclosed to listeners in init_net. * Availability impact realistic: +1 IKE daemons inside non-init netns can miss their own migration notifications, breaking MOBIKE/address-update handling. * Integrity impact plausible in paranoid interpretation: +1 A userspace IKE daemon may observe or react to migration events from the wrong namespace, creating limited control-plane confusion. * Requires CAP_NET_ADMIN in typical deployments: -2 conservative Triggering XFRM MIGRATE normally requires privileged XFRM control-plane access. * Privilege penalty reduced in paranoid score: -1 or 0 In container or delegated-netns deployments, reduced-capability root or service accounts with CAP_NET_ADMIN in their own namespace are not equivalent to full host root. No memory corruption, UAF, OOB access, refcount bug, or LPE primitive is indicated by the patch. ## 3. Reachability analysis The bug is locally triggerable through the XFRM/PF_KEY control plane, not by ordinary network packets. In typical host deployments, the caller needs CAP_NET_ADMIN or equivalent authority to issue XFRM migration operations, so the conservative interpretation is privileged local access. In containerized or delegated network namespace setups, a less trusted namespace administrator may be able to trigger the path, while the resulting notification is incorrectly delivered to init_net listeners. XFRM/IPsec is not universal by default, but it is a core Linux networking security subsystem and should not be treated as an obscure hardware-only path. ## 4. Severity interpretation This behaves like an actionable Moderate issue, not a memory-corruption Important issue. The main risk is namespace isolation failure and control-plane information exposure, plus broken IKE/MOBIKE behavior inside non-init namespaces. There is no evidence of kernel memory corruption, privilege escalation, arbitrary write, or code execution. However, because it crosses a namespace security boundary and exposes IPsec migration metadata, it should not be auto-closed as a trivial correctness fix. ## 5. One-sentence report phrase XFRM MIGRATE notifications were incorrectly multicast in init_net instead of the caller network namespace, exposing IPsec migration metadata across namespace boundaries and breaking per-netns IKE migration handling. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Manual review is required because this is a cross-namespace control-plane isolation issue involving IPsec/XFRM metadata, and the practical severity depends on container delegation, CAP_NET_ADMIN exposure, and whether init_net IKE listeners can observe or act on non-init netns migration events. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: xfrm: route MIGRATE notifications to caller's netns Commit: bafc7d0774b9bf52909c70ed990bc5ccf7ec4bad Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bafc7d0774b9bf52909c70ed990bc5ccf7ec4bad Commit description: xfrm_send_migrate() in net/xfrm/xfrm_user.c and pfkey_send_migrate() in net/key/af_key.c both hardcode &init_net for the multicast that announces a successful XFRM_MSG_MIGRATE / SADB_X_MIGRATE. XFRM_MSG_MIGRATE arrives on a per-netns NETLINK_XFRM socket, and the rest of the xfrm/af_key netlink path was made netns-aware in 2008. The other 14 multicast paths in xfrm_user.c route their event using xs_net(x), xp_net(xp) or sock_net(skb->sk); only the migrate path was missed. Two consequences of the init_net hardcoding: 1. The notification (selector, old/new endpoint addresses, and the km_address) is delivered to listeners on init_net's XFRMNLGRP_MIGRATE / pfkey BROADCAST_ALL groups rather than on the issuing netns. An IKE daemon running in init_net therefore receives migration notifications originating from any other netns on the host. 2. An IKE daemon running inside a non-init netns and subscribed to its own XFRMNLGRP_MIGRATE / pfkey groups never receives the notification of its own migration. IKEv2 MOBIKE / address-update handling inside a netns is silently broken. Thread struct net through km_migrate() and the xfrm_mgr.migrate function pointer, drop the &init_net override in xfrm_send_migrate() and pfkey_send_migrate(), and pass the caller's net (already in scope in xfrm_migrate() via sock_net(skb->sk)) all the way down. struct xfrm_mgr is in-tree only and not exported as a stable API, so the function-pointer signature change is internal. pfkey_broadcast() is already netns-aware via net_generic(net, pfkey_net_id) since the pernet conversion. The five other pfkey_broadcast() callers in af_key.c already pass xs_net(x), sock_net(sk) or a per-netns net, so this only removes the &init_net outlier. Fixes: 5c79de6 ("[XFRM]: User interface for handling XFRM_MSG_MIGRATE") Cc: stable@vger.kernel.org # v5.15+ Signed-off-by: Maoyi Xie Signed-off-by: Steffen Klassert Signed-off-by: Greg Kroah-Hartman Changed files: net/xfrm/xfrm_user.c net/key/af_key.c include/net/xfrm.h net/xfrm/xfrm_policy.c net/xfrm/xfrm_state.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=bafc7d0774b9bf52909c70ed990bc5ccf7ec4bad ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-63914 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63914 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:L/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L The Best / paranoid CVSS score: 5.3 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: 4 Paranoid ActionableScore: 5 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: MODERATE KPANIC detected for this report: YES Published priority for this report (same as in Subject): MODERATE 7.0 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).