From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97472][MODERATE REGULAR] ipv6: addrconf: fix temp address generation after prefix deprecation [ Upstream Date: Thu, 24 Sep 2026 14:52:10 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97472 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 3 X-AL-KERNEL-ActionableScore-Lower: 2 X-AL-KERNEL-Commit: bff7b87dfa28a1502c18d0c6f1fadda5162fa854 List-Id: CVE: CVE-2026-97472 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: ipv6: addrconf: fix temp address generation after prefix deprecation [ Upstream Commit: bff7b87dfa28a1502c18d0c6f1fadda5162fa854 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bff7b87dfa28a1502c18d0c6f1fadda5162fa854 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97472 Analysis date: Thu, 24 Sep 2026 14:52:10 -0400 ActionableScore: 3 ActionableScore lower bound: 2 Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97472 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97472 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 REGULAR 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-2026-97472 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-97472 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L';*CWE-664;CWE-693;CWE-359;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.4';DESCR 'An IPv6 temporary address regeneration failure can occur after a Router Advertisement temporarily deprecates a prefix and later restores it. The latest temporary address retains its regeneration state, and after it expires the kernel can fail to create a replacement RFC 8981 privacy address for that prefix. An attacker must be able to send or spoof Router Advertisements on the same local network segment. For the CVSS the PR:N value is used because no local account or code execution on the target is required when the attacker controls an adjacent network Router Advertisement source. The issue is network-adjacent rather than Internet reachable. Base impact is limited availability or privacy address functionality loss. For the paranoid score, limited confidentiality impact is possible because connections may fall back to a more stable IPv6 source address and become more linkable. No memory corruption, kernel crash, privilege escalation, or direct information disclosure primitive is indicated by the patch.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) YES REMOTE OOB NETWORK IPV6 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 2 * Conservative score: 2 * Raw paranoid score: 3 * Paranoid score: 3 * Final recommended bucket: **Borderline / manual review recommended**:: No floor or cap was applied. 2. Signal breakdown Conservative signals: * +2 Directly network-triggerable from an adjacent network. A malicious device or rogue router on the same IPv6 L2 segment can send Router Advertisements that exercise the affected prefix lifetime handling. This is network-adjacent reachability, not unrestricted Internet reachability. Paranoid-only signal: * +1 Limited confidentiality or privacy impact. The failure can prevent future RFC 8981 temporary-address regeneration. If applications later fall back to a stable IPv6 address, the attacker may be able to correlate activity that temporary privacy addresses were intended to reduce. This is limited linkability exposure, not protected-data disclosure. Important non-awarded signals: * No UAF, stale pointer, refcount error, OOB access, double release, or memory corruption is established. * No arbitrary write, controlled reclaim, callback control, or attacker-controlled kernel object reuse is demonstrated. * No kernel crash, panic, persistent resource exhaustion, or strong availability consequence is established. * No privilege escalation, authorization bypass, namespace escape, or integrity impact is established. * No extra availability point is awarded. Failure to regenerate a temporary address is not equivalent to a reliable host or network DoS. * No race penalty is applied. The required Router Advertisement sequence is a protocol-state sequence, not a demonstrated narrow kernel concurrency race. * No niche-subsystem penalty is applied. IPv6 SLAAC and Router Advertisement processing are ordinary networking functionality where enabled. 3. Reachability analysis The evaluated attacker is an adjacent-network attacker, such as a device connected to the same IPv6 broadcast domain or an attacker able to spoof Router Advertisements on that segment. The complete trigger does not require local code execution, a local account, CAP_NET_ADMIN, host root, or control of the target network namespace. The attacker sends Router Advertisements that first deprecate a prefix through Preferred Lifetime zero or expiration and later restore the prefix. The vulnerable state becomes relevant when the affected temporary address later reaches normal expiration. The attack requires that IPv6 Router Advertisements are accepted on the target interface and that IPv6 temporary privacy addressing is enabled and used for the affected prefix. Router Advertisement Guard, trusted switch-port controls, static IPv6 configuration, disabled IPv6, disabled temporary addresses, or a network without attacker access to the same L2 segment materially reduce exposure. Namespace-scoped privilege is not relevant to the evaluated attack path. The trigger is external adjacent-network traffic rather than a namespace-local privileged API operation. HostAdminRequired is NO because below-host-admin reachability is positively established through unauthenticated local-link Router Advertisements. 4. Primitive and severity interpretation The primitive is a protocol-state and privacy-address lifecycle logic failure. After a prefix is deprecated, temporary-address regeneration may fail but increments regen_count. When a later Router Advertisement restores the prefix, the state is not reset. After the existing temporary address expires, the kernel can incorrectly avoid creating a replacement temporary address. This is not an active-object lifetime bug, UAF, memory corruption, ownership violation, or authorization bypass. The patch only restores the temporary-address regeneration state for the newest temporary address associated with a restored prefix. The demonstrated practical consequence is loss of expected RFC 8981 temporary-address renewal for one IPv6 prefix. The likely operational impact is reduced privacy-address functionality and possible application fallback to a stable IPv6 source address. The paranoid interpretation permits limited linkability exposure if that fallback occurs, but it does not establish exposure of protected kernel memory, user data, credentials, or other sensitive resources. PrimitiveClass is NONE. ImportantCandidate is NO because no Important-preserving corruption, ownership, authorization, or security-boundary primitive is established. AutoDowngradeAllowed is YES because the issue is a bounded logic/privacy degradation without unresolved kernel corruption leverage. Manual review remains recommended because the trigger is attacker-controlled adjacent-network Router Advertisement traffic and exposure depends on deployment-specific IPv6, SLAAC, and privacy-address settings. 5. One-sentence report phrase An adjacent-network attacker able to send spoofed IPv6 Router Advertisements can cause temporary privacy address regeneration to remain disabled after prefix deprecation and restoration, potentially reducing RFC 8981 privacy protections and increasing source-address linkability. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Verify whether affected systems accept Router Advertisements from untrusted L2 peers and use IPv6 temporary privacy addresses on exposed interfaces. Urgency is generally low where Router Advertisement sources are trusted or RA Guard is enforced. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ipv6: addrconf: fix temp address generation after prefix deprecation [ Upstream Commit: bff7b87dfa28a1502c18d0c6f1fadda5162fa854 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bff7b87dfa28a1502c18d0c6f1fadda5162fa854 Changed files: net/ipv6/addrconf.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=bff7b87dfa28a1502c18d0c6f1fadda5162fa854 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97472 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97472 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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L The Best / paranoid CVSS score: 5.4 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: 2 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: MODERATE KPANIC detected for this report: NO Published priority for this report (same as in Subject): MODERATE REGULAR 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).