From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98723][IMPORTANT] nvmet: copy the hostid into the ctrl before creating PR pc_refs [ Upstream Date: Sat, 24 Oct 2026 02:47:42 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98723 X-AL-KERNEL-Priority: IMPORTANT X-AL-KERNEL-Severity: IMPORTANT X-AL-KERNEL-Base-Severity: IMPORTANT X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 7 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: d3d6d7efdacc08616d23b3ac42272a494951dc0f List-Id: CVE: CVE-2026-98723 Priority: IMPORTANT AL-KERNEL base severity: IMPORTANT KPANIC flag: NO Patch: nvmet: copy the hostid into the ctrl before creating PR pc_refs [ Upstream Commit: d3d6d7efdacc08616d23b3ac42272a494951dc0f Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d3d6d7efdacc08616d23b3ac42272a494951dc0f Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98723 Analysis date: Sat, 24 Oct 2026 02:47:42 -0400 ActionableScore: 7 ActionableScore lower bound: unknown Actionable bucket: Strong Important candidate Manual review required: YES Summary: An authorized NVMe host can successfully preempt a registrant while the target fails to abort and drain that victim’s in-flight I/O, violating persistent-reservation fencing. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98723 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98723 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: IMPORTANT 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-2026-98723 IMPORTANT https://www.kernelcve.org/list/?q=CVE-2026-98723 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=3 LEGACY=IMPORTANT RESULT=DIFF INDEPENDENT_LEGACY=IMPORTANT INDEPENDENT_RESULT=DIFF TEMP_KPANIC_MERGE=IMPORTANT_WINS_DISAGREEMENT PRE_MERGE_LEGACY=IMPORTANT (final Legacy and Aegis differ; FINAL: IMPORTANT, Aegis: MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H';CWE-665;CWE-863;Other CVSS 'AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '7.3';DESCR 'This is an initialization ordering and reservation enforcement flaw in the NVMe target. nvmet_ctrl_init_pr snapshots ctrl hostid into each per controller namespace pc_ref before the real hostid is copied from the connection data, so the stored value is the nil UUID. During Persistent Reservation Preempt and Abort, nvmet_pr_set_ctrl_to_abort cannot match the displaced registrant and therefore does not kill or drain its in flight I/O even though the preempting host receives success. The affected path requires persistent reservations and a namespace that exists before the controller connects, which also covers reconnects. For the CVSS the PR:L value reflects that the attacker must be an authorized NVMe host able to connect to the target and issue reservation commands. Continued victim I/O can violate storage fencing and may cause stale writes, data consistency damage, or service disruption across hosts sharing the namespace. There is no evidence of kernel memory corruption, information disclosure, or direct code execution. Automated impact decision path. The original SimpleNet classifier selected MODERATE. The primary LLM estimated paranoid CVSS 7.3 and the production ActionableScore returned 7 with recommendation Strong Important candidate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE to MODERATE_KPANIC because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE_KPANIC to IMPORTANT because the ActionableScore threshold rule was applied. KP and FD specialist checks stage IMPORTANT to IMPORTANT because a specific evidence based protection or manual review veto was applied. final reconciliation stage IMPORTANT to IMPORTANT because KP specialist did not establish a qualifying panic. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist produced a review artifact and its decision was processed by the applicable downgrade and preservation rules. Exact triggered rule markers were INCREASED_TO_MODERATE7_FROM_MODERATE_BASED_ON_GUESSCVSS and INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHERTHAN5 and V59_LEGACY_CLASSA_KP_VETO and MANUAL_REVIEW_REQUIRED and TEMP_KPANIC_MERGE_IMPORTANT_WINS and KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 3.5 and ActionableScore 3 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is IMPORTANT.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate (with actual score 7) MAYBE INIT NVME IMPROVEONLY DEBUGFS LINUS INCREASED_TO_MODERATE7_FROM_MODERATE_BASED_ON_GUESSCVSS INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHERTHAN5 V59_LEGACY_CLASSA_KP_VETO MANUAL_REVIEW_REQUIRED TEMP_KPANIC_MERGE_IMPORTANT_WINS KPANIC_UNSUPPORTED_REMOVED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=7 PrimitiveClass=CLASS_A RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=YES ManualReview=REQUIRED AutoDowngradeAllowed=NO RequiresHostUID0=NO AuthorizationDecisionBypass=NO ProtectedResourceImpact=CONFIRMED B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 7. * Conservative score: 7; no floor or cap applied. * Raw paranoid score: 7. * Paranoid score: 7; no additional speculative effects scored. * Final recommended bucket: **Strong Important candidate**:: 2. Signal breakdown * +2 — Network-reachable storage-policy bypass: an authorized NVMe host can invoke Persistent Reservation Preempt and Abort against the target. * +2 — Material security-boundary/policy failure: the nil `pc_ref->hostid` prevents identification, killing, and draining of the displaced registrant’s in-flight I/O. * +1 — Practical chain: connect snapshots the nil UUID, reservation preemption later fails the host-ID match, and the command reports success while victim I/O continues. * +1 — Integrity plausible: continued victim writes can violate reservation fencing and alter shared namespace data after successful preemption. * +1 — Important storage path: this affects NVMe persistent reservations and multi-host shared-storage consistency. * No UAF, OOB access, arbitrary write, kernel-memory corruption, disclosure, LPE, or proven kernel crash is shown. * No extra availability point: service disruption is plausible, but no distinct reliable target-host crash or persistent outage is established. 3. Reachability analysis The grounded attacker is an authorized NVMe fabric host able to connect and issue reservation commands, not an ordinary unauthenticated network peer. This is below effective target-host administration and does not require target-host UID 0. Persistent reservations, a pre-existing namespace, and host authorization are required service configuration; reconnects are explicitly affected. Linux user/net namespace capabilities are not part of the shown trigger. 4. Primitive and severity reading The primitive is an initialization-ordering failure in active reservation identity state. `nvmet_ctrl_init_pr()` snapshots a zero host ID before the connection host ID is copied; its sole later consumer therefore fails to abort and drain the preempted host’s I/O. This is CLASS_A storage-fencing/policy bypass, not memory corruption. `AuthorizationDecisionBypass=NO` and B4 is not confirmed because the patch does not show a conventional authorization guard changing a command from DENY to ALLOW; it shows failure to enforce the post-admission abort/drain semantics. The protected namespace and fencing impact are nevertheless concrete. Data corruption and disruption are plausible, while specific stale writes or permanent damage are not guaranteed. 5. One-sentence report phrase An authorized NVMe host can successfully preempt a registrant while the target fails to abort and drain that victim’s in-flight I/O, violating persistent-reservation fencing. 6. Manual review advice MANUAL CHECK REQUIRED The confirmed cross-host storage-fencing failure has material integrity implications and must not be auto-downgraded despite the absence of kernel memory corruption or LPE. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: nvmet: copy the hostid into the ctrl before creating PR pc_refs [ Upstream Commit: d3d6d7efdacc08616d23b3ac42272a494951dc0f Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d3d6d7efdacc08616d23b3ac42272a494951dc0f Changed files: drivers/nvme/target/core.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=d3d6d7efdacc08616d23b3ac42272a494951dc0f ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98723 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98723 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:L/PR:L/UI:N/S:U/C:N/I:L/A:L The Best / paranoid CVSS vector: AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H The Best / paranoid CVSS score: 7.3 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: unknown Paranoid ActionableScore: 7 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: IMPORTANT KPANIC detected for this report: NO Published priority for this report (same as in Subject): IMPORTANT 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).