From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-53214][LOW] ipv6: Fix a potential NPD in cleanup_prefix_route() [ Upstream Date: Mon, 29 Jun 2026 10:24:12 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-53214 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: 5f82b02b4059ddc06e4fcfd057bfb59fd6885cd2 List-Id: CVE: CVE-2026-53214 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: ipv6: Fix a potential NPD in cleanup_prefix_route() [ Upstream Commit: 5f82b02b4059ddc06e4fcfd057bfb59fd6885cd2 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5f82b02b4059ddc06e4fcfd057bfb59fd6885cd2 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53214 Analysis date: Mon, 29 Jun 2026 10:24:12 -0400 ActionableScore: 3 ActionableScore lower bound: 1 Actionable bucket: Borderline Ordinary Moderate / namespace exposure check Manual review required: NO Summary: A local actor with IPv6 rtnetlink configuration privileges, or potentially an unprivileged user through delegated network namespaces, can trigger a NULL pointer dereference in `cleanup_prefix_route()` by causing `addrconf_get_prefix_route()` to return `fib6_null_entry`, resulting in a kernel crash. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53214 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53214 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-2026-53214 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:N/A:H';**CWE-476;*CWE-20;CWE-703;BEST CVSS score: '5.5';DESCR 'cleanup_prefix_route can dereference fib6_null_entry after addrconf_get_prefix_route returns the IPv6 null route sentinel whose fib6_table pointer is NULL. A local actor can trigger the vulnerable path through rtnetlink IPv6 address deletion when the route lookup returns this sentinel, causing a kernel NULL pointer dereference and system crash. For the CVSS the PR:L is used because reliable triggering requires local code execution and netlink based network configuration privileges, commonly CAP_NET_ADMIN in a network namespace. The issue is not directly network reachable and is not triggered by ordinary packet traffic. Impact is denial of service only because the patch evidence shows a NULL pointer dereference and does not indicate UAF, OOB access, arbitrary write, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Borderline Ordinary Moderate / namespace exposure check (with actual score 2) SKIP CVE-2026-53214 SKIP The Fixes patch not applied yet, so unlikely that actual: 5eb902b8e7193cdcb33242af0a56502e6b5206e9 YES NO NO unknown MAYBE REMOTE KASAN OOB LOCK NULLPTR NETWORK HARDWARE IPV6 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 Ordinary Moderate / namespace exposure check**:: ## 2. Signal breakdown Conservative scoring: * Reliable kernel crash / strong DoS: +1 The trace shows a NULL pointer dereference through `fib6_null_entry->fib6_table == NULL` followed by `spin_lock_bh(&table->tb6_lock)`. * Broad/default/common subsystem: +1 IPv6 addrconf and rtnetlink are core networking configuration paths, although this is not a packet receive path. * Requires CAP_NET_ADMIN in typical deployments: -2 The demonstrated path is `inet6_rtm_deladdr()` via rtnetlink IPv6 address deletion, normally requiring CAP_NET_ADMIN. Conservative total: 1 Paranoid adjustment: * Local unprivileged trigger: +1 On systems with unprivileged user namespaces and network namespaces enabled, an unprivileged local user may obtain CAP_NET_ADMIN inside a new netns and exercise this path. Paranoid total: 3 Not counted: * No generic memory corruption. This is a NULL pointer dereference on a sentinel route object, not UAF, OOB write, double free, arbitrary write, or object reclaim. * No privilege escalation signal. The patch does not show a corruption primitive suitable for LPE. * No remote reachable signal. Ordinary IPv6 packets do not directly trigger this path. ## 3. Reachability analysis The realistic trigger is local rtnetlink control-plane activity that deletes an IPv6 address and reaches `cleanup_prefix_route()`. In the initial network namespace this usually requires CAP_NET_ADMIN, so conservative scoring treats it as privileged. In environments allowing unprivileged user namespaces plus network namespaces, a local unprivileged user may create a namespace, gain CAP_NET_ADMIN inside it, and potentially trigger the bug against the host kernel, which justifies the paranoid score. The path is not directly network-triggerable and is not part of ordinary packet processing. ## 4. Severity interpretation This behaves like an ordinary Moderate local DoS in the conservative case. The worst credible interpretation is borderline actionable only because namespace delegation may reduce the effective privilege requirement. There is no evidence of a practical memory corruption primitive or privilege escalation path. The theoretical impact remains kernel crash availability loss, not confidentiality or integrity compromise. ## 5. One-sentence report phrase A local actor with IPv6 rtnetlink configuration privileges, or potentially an unprivileged user through delegated network namespaces, can trigger a NULL pointer dereference in `cleanup_prefix_route()` by causing `addrconf_get_prefix_route()` to return `fib6_null_entry`, resulting in a kernel crash. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: not because of memory corruption, but to verify product-specific namespace policy. If unprivileged user namespaces or delegated CAP_NET_ADMIN are disabled, this can likely be treated as ordinary Moderate and auto-closed for urgent-response purposes. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ipv6: Fix a potential NPD in cleanup_prefix_route() [ Upstream Commit: 5f82b02b4059ddc06e4fcfd057bfb59fd6885cd2 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5f82b02b4059ddc06e4fcfd057bfb59fd6885cd2 Changed files: mm/kasan/common.c kernel/locking/lockdep.c kernel/locking/spinlock.c net/ipv6/addrconf.c net/core/rtnetlink.c net/netlink/af_netlink.c net/socket.c arch/x86/entry/syscall_64.c arch/x86/entry/entry_64.S 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=5f82b02b4059ddc06e4fcfd057bfb59fd6885cd2 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53214 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53214 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: Not available 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: 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).