From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98592][MODERATE 7.0] net: spacemit: clear TX descriptor on fragment mapping failure [ Upstream Date: Sat, 24 Oct 2026 10:15:52 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98592 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: ca9986cc824f2feb79b4a83e5f6f4c24c2140448 List-Id: CVE: CVE-2026-98592 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: net: spacemit: clear TX descriptor on fragment mapping failure [ Upstream Commit: ca9986cc824f2feb79b4a83e5f6f4c24c2140448 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ca9986cc824f2feb79b4a83e5f6f4c24c2140448 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98592 Analysis date: Sat, 24 Oct 2026 10:15:52 -0400 ActionableScore: 5 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review Manual review required: YES Summary: A local sender can reach a TX rollback flaw that leaves OWN-marked descriptors referencing unmapped DMA buffers, permitting later privileged DMA consumption and possible NIC failure or stale-memory transmission. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98592 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98592 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-2026-98592 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98592 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=MODERATE_KPANIC RESULT=SAME (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:N/A:H';*CWE-416;*CWE-672;*CWE-200;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '5.3';DESCR 'A TX fragment DMA mapping failure can leave descriptors after old_head marked OWN even though emac_free_tx_buf has unmapped their buffers and software has rolled the ring head back. On the next transmission the DMA engine may advance into a stale descriptor and read from an expired DMA address, causing an IOMMU fault, NIC malfunction, or unintended transmission of data from memory later associated with that address. Reliable triggering requires local packet generation with fragmented skbs plus a DMA mapping failure, so AC:H is appropriate and direct remote reachability is not established. For the CVSS the PR:L value reflects that an unprivileged local process can originate traffic, while no administrative privilege is inherently needed, although practical control over the mapping failure is uncertain. The supported primitive is a stale TX DMA read rather than a DMA write, so limited confidentiality and availability impact are defensible but kernel memory modification or privilege escalation is not established. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 5.3 and the production ActionableScore returned 5 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to MODERATE_KPANIC because the ActionableScore threshold rule was applied. 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 has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH and INCREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN5. The independent weaker Aegis shadow evaluated CVSS 2.7 and ActionableScore 2 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5) MAYBE REMOTE NETWORK DMAorINTERRUPT PACKET DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH KPANIC INCREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN5 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=4 PrimitiveClass=CLASS_B RealUAF=YES HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=YES ManualReview=REQUIRED AutoDowngradeAllowed=NO RequiresHostUID0=NO AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 4. * Conservative score: 4; no floor or cap applied. * Raw paranoid score: 5. * Paranoid score: 5; no floor or cap applied. * Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**:: 2. Signal breakdown * +2 real lifetime violation: descriptor ownership remains active after its DMA mappings are unmapped; the DMA engine may subsequently consume the expired addresses. * +1 local unprivileged trigger: an ordinary local process can originate fragmented transmit traffic without host-administrator privilege, although inducing the mapping failure is uncertain. * +1 sensitive active DMA-descriptor corruption: rollback leaves an OWN-marked descriptor containing stale DMA addresses, and the privileged DMA engine later consumes it. * Paranoid +1 confidentiality plausible: address reuse could make the NIC read and transmit data later associated with the stale DMA address. This is technically possible but not demonstrated. * No OOB write, DMA write, controlled payload/target, reclaim, arbitrary kernel access, host panic, or LPE is shown. * No separate availability point: supplied evidence supports an IOMMU fault or NIC malfunction, not a host-wide crash. * NEW52/B5-R does not apply: there is no retry-accumulated heap OOB write. * B3-PENDING and B4-PENDING do not apply: no shared-backing write or authorization decision exists. 3. Reachability analysis The assessed actor is a below-host-admin local process generating transmit traffic. No capability, host UID 0, prior privileged configuration, namespace privilege, or special device assignment is shown as necessary. The actor can influence skb fragmentation and invoke the TX path, but reliable control of DMA mapping failure is not established; therefore reliability is high-complexity without being a proven privilege barrier. Spacemit K1 Ethernet hardware is required, but the evidence does not establish that it is rare enough for a hardware penalty. 4. Primitive and severity reading The primitive is an active stale DMA descriptor: error rollback unmaps buffers and frees the skb but fails to clear descriptors already marked OWN. This is an asynchronous post-lifetime/use-after-unmap Class B condition, not a heap UAF or DMA write. The privileged device later consumes stale structured address and ownership state. A device fault is supported; unintended data transmission is plausible but unconfirmed. ImportantCandidate is YES because attacker-invocable active descriptor corruption reaches a privileged DMA consumer and the resulting host-memory disclosure boundary remains unresolved. Auto-downgrade is disallowed pending confirmation of IOMMU containment, address reuse behavior, and whether stale data can reach the wire. 5. One-sentence report phrase A local sender can reach a TX rollback flaw that leaves OWN-marked descriptors referencing unmapped DMA buffers, permitting later privileged DMA consumption and possible NIC failure or stale-memory transmission. 6. Manual review advice MANUAL CHECK REQUIRED Confirm mapping-failure inducibility, IOMMU behavior, descriptor prefetch/advance semantics, DMA-address reuse, and whether any stale data can be transmitted. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net: spacemit: clear TX descriptor on fragment mapping failure [ Upstream Commit: ca9986cc824f2feb79b4a83e5f6f4c24c2140448 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ca9986cc824f2feb79b4a83e5f6f4c24c2140448 Changed files: drivers/net/ethernet/spacemit/k1_emac.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=ca9986cc824f2feb79b4a83e5f6f4c24c2140448 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98592 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98592 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:L/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H 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).