From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99045][MODERATE 7.0] ibmveth: h_free logical LAN on open-fail after register Date: Mon, 26 Oct 2026 20:14:38 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99045 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: 3 X-AL-KERNEL-ActionableScore-Lower: 2 X-AL-KERNEL-Commit: decb4d4ead2c71ef698727734ab5024a872eb372 List-Id: CVE: CVE-2026-99045 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: ibmveth: h_free logical LAN on open-fail after register Commit: decb4d4ead2c71ef698727734ab5024a872eb372 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=decb4d4ead2c71ef698727734ab5024a872eb372 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99045 Analysis date: Mon, 26 Oct 2026 20:14:38 -0400 ActionableScore: 3 ActionableScore lower bound: 2 Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: An ibmveth open-failure unwind can unmap a PHYP-owned buffer-list page without deregistering the logical LAN, creating a constrained but unresolved DMA-lifetime risk. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99045 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99045 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-2026-99045 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-99045 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=MODERATE_KPANIC RESULT=SAME V39_AEGIS_ONE_STEP_UP=MODERATE->MODERATE_KPANIC (final reconciliation agrees; DECISION: both MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';CWE-404;CWE-459;*CWE-672;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.8';DESCR 'An ibmveth open failure after h_register_logical_lan can reach buffer pool cleanup lacking h_free_logical_lan, leaving PHYP ownership active while the buffer list page is unmapped. This is not a demonstrated kernel UAF or arbitrary write, but later PHYP access to the stale page could cross the page lifetime boundary and may affect reused memory. For the CVSS the PR:L value is selected because triggering requires a local process able to open or administer the ibmveth interface, typically through CAP_NET_ADMIN or an equivalent service context. AC:H reflects the additional need for RX pool allocation or IRQ setup to fail after registration. The issue is not directly network reachable. The base impact is limited resource retention and device availability, while the paranoid CIA:LLH vector covers unresolved confidentiality, integrity, and host availability consequences from possible hypervisor access after unmap. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 5.8 and the production ActionableScore returned 3 with recommendation Borderline / manual review recommended. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold rule was applied. final reconciliation stage MODERATE to MODERATE_KPANIC because the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 1.9 and ActionableScore 0 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 MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) MAYBE REMOTE INIT SIMPLEFIX NETWORK LOG LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 KPANIC V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 PrimitiveClass=CLASS_B RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 2. * Conservative score: 2; no floor or cap applied. * Raw paranoid score: 3. * Paranoid score: 3; no floor or cap applied. * Final recommended bucket: **Borderline / manual review recommended**:: 2. Signal breakdown * +1 concrete persistent resource/ownership leak: after successful `h_register_logical_lan()`, RX-pool allocation failure reaches cleanup without deregistering, leaving PHYP ownership active. * +1 weak lifetime/ownership corruption candidate: cleanup unmaps/frees backing while PHYP still owns the buffer-list page; the fix restores deregistration before that teardown. * Paranoid +1 device availability concern: retained PHYP registration may interfere with device recovery or reopening, but host-wide failure is not established. * No confirmed DMA access or write after unmap, heap OOB write, UAF dereference, arbitrary target/payload, disclosure, or kernel crash is shown. * NEW52/B5-R does not apply: there is no retry-accumulated OOB write or later consumption of corrupted structured state. * No Important-preserving active-state chain: the ownership defect is proven, but a later PHYP consumer touching reused memory is only possible, not demonstrated. 3. Reachability analysis The vulnerable path is `ibmveth_open()` after logical-LAN registration and requires subsequent RX-pool allocation or IRQ setup failure. Interface-opening authority is not established by the supplied source; CAP_NET_ADMIN is plausible but its namespace scope and the complete below-host-admin path are unproven. There is no remote packet trigger. IBM PHYP/ibmveth support is required, but no hardware rarity penalty is applied from the supplied evidence. 4. Primitive and severity reading The exact primitive is an external ownership/lifetime mismatch: PHYP remains registered as owner while the kernel tears down the page. This is CLASS_B state-lifetime risk, not a confirmed UAF or write. The shown effect is leaked registration/ownership; stale hypervisor access to reused memory is speculative. Consequently ImportantCandidate is NO and automatic Moderate handling remains permissible, but manual review is advisable because the missing deregistration precedes memory teardown. 5. One-sentence report phrase An ibmveth open-failure unwind can unmap a PHYP-owned buffer-list page without deregistering the logical LAN, creating a constrained but unresolved DMA-lifetime risk. 6. Manual review advice MANUAL CHECK RECOMMENDED Confirm whether PHYP can access the page after this failure and whether reopening or page reuse produces a write, crash, or cross-owner effect. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ibmveth: h_free logical LAN on open-fail after register Commit: decb4d4ead2c71ef698727734ab5024a872eb372 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=decb4d4ead2c71ef698727734ab5024a872eb372 Commit description: ibmveth_open() registers the logical LAN, then allocates the RX buffer pools. A pool failure jumps to out_free_buffer_pools without h_free_logical_lan(), so PHYP still owns the buffer-list page when it is unmapped. request_irq() failure already issued the hypercall before taking the same label. Move that h_free to the shared post-register unwind so both paths deregister before the buffer list is unmapped. Fixes: d43732c ("ibmveth: properly unwind on init errors") Cc: stable@vger.kernel.org Signed-off-by: Mingming Cao Reviewed-by: Dave Marquardt Link: https://patch.msgid.link/7a56fbfb9e0674f011f4e310fbd7dfd8e67c30aa.1790357373.git.mmc@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman Changed files: drivers/net/ethernet/ibm/ibmveth.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=decb4d4ead2c71ef698727734ab5024a872eb372 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99045 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99045 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:L/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 5.8 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: 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).