From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-64035][MODERATE 7.0] igc: set tx buffer type for SMD frames [ Upstream Date: Sun, 19 Jul 2026 16:48:30 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-64035 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: 6 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: 1f83545f432d106d5fc71d3997b2d382104ebcc4 List-Id: CVE: CVE-2026-64035 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: igc: set tx buffer type for SMD frames [ Upstream Commit: 1f83545f432d106d5fc71d3997b2d382104ebcc4 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1f83545f432d106d5fc71d3997b2d382104ebcc4 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64035 Analysis date: Sun, 19 Jul 2026 16:48:30 -0400 ActionableScore: 6 ActionableScore lower bound: 3 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: A stale TX buffer type in the Intel igc SMD frame path can cause TX completion to use an XDP or XSK cleanup path for an SKB-backed buffer, creating a plausible wrong-free or lifetime-corruption condition with local DoS impact and possible higher impact requiring manual review. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64035 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64035 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-2026-64035 MODERATE CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-843;CWE-763;*CWE-416;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A stale tx buffer type in the igc driver can make SMD frame TX completion use a cleanup path that does not match the object actually stored in the reused descriptor. The affected entry is initialized as an skb but may still carry an older XDP or XSK type, so completion can treat the buffer as the wrong object type and may free or release it incorrectly. For the CVSS the PR:L is used in the paranoid score because reliable triggering may be possible for a local user or service with delegated network administration, XDP, XSK, or reduced capability access rather than only full host root. The issue is not directly network reachable and depends on Intel igc hardware plus frame preemption verification and TX buffer reuse conditions. Impact is at least local denial of service via driver or kernel crash, and in worst case may allow confidentiality or integrity impact due to wrong cleanup path memory corruption. YES REQUIRES MANUAL CHECK.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5) YES REMOTE SIMPLEFIX NETWORK SKB KPANIC KPANIC DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN7 YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=6 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: 3 * Paranoid score: 6 * Final recommended bucket: **Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative signals: * Memory corruption, Weak/indirect corruption candidate: +1 Stale `igc_tx_buffer->type` can make TX completion interpret an SKB-backed entry as XDP or XSK backed state. This is an object interpretation / cleanup-path mismatch, but the patch does not show attacker-controlled replacement, arbitrary write, or callback control. * Real lifetime corruption: +1 The wrong TX completion cleanup path can plausibly release, unmap, or free the wrong object type. This is a lifetime-management concern rather than pure bookkeeping. * Reliable kernel crash / strong DoS: +1 A wrong cleanup path in a NIC TX completion path can realistically crash the driver or kernel, even if no exploit primitive is demonstrated. Conservative deductions / limits: * Requires admin/root/CAP_NET_ADMIN in typical deployments: -2 considered but not fully dominant in final triage because the bug is in a driver lifetime path and may be reachable through delegated network administration or service-controlled setup. * No remote/network-triggerable score. The issue is not caused by incoming packets alone. * No strong LPE score in the conservative result. The patch does not demonstrate reclaim, controlled replacement, write-after-free, function pointer control, or arbitrary write. Paranoid additional signals: * Weak LPE concern: +1 The stale XDP/XSK type can cause cleanup of an object under the wrong semantic type. This is not a proven LPE primitive, but it is enough to justify manual review. * Privileged kernel/device-management memory corruption path: +1 The bug is in a trusted NIC driver TX completion ownership path involving SKB/XDP/XSK cleanup semantics. * Confidentiality impact plausible: +1 Only for paranoid scoring. If the wrong cleanup path creates a real UAF or object confusion, limited information exposure may become possible. * Integrity impact plausible: +1 Only for paranoid scoring. If the wrong cleanup path becomes a real UAF/type confusion primitive, integrity impact cannot be ruled out without completion-path review. ## 3. Reachability analysis The likely trigger requires Intel `igc` hardware, frame preemption verification / SMD frame handling, and prior reuse of a TX buffer entry that previously carried an XDP or XSK type. Reliable triggering likely requires local control over NIC configuration or related XDP/XSK/FPE setup, commonly requiring root or `CAP_NET_ADMIN`. Namespaces and containers may matter. If a container root, network-management service, or reduced-capability account has delegated network administration or AF_XDP/XDP-related control, the practical privilege level may be closer to PR:L than full host root. The path is not directly remotely reachable. Network traffic alone is not enough based on the patch. The exposure is hardware and configuration dependent, but the affected code is in a real NIC driver TX lifecycle path, so it should not be treated as a harmless cleanup-only fix. Call-site confidence: medium. The provided patch shows only initialization of `buffer->type`, but the commit explicitly states that TX completion can use the wrong cleanup path. ## 4. Severity interpretation This behaves more like an actionable Moderate than an ordinary Moderate. The realistic impact is probably local DoS through driver or kernel crash under specific hardware/configuration conditions. The theoretical risk is higher because stale object type in a reused TX buffer can turn into wrong free, wrong unmap, UAF, or type confusion depending on TX completion behavior. It is not a Strong Important candidate by default because the patch does not demonstrate attacker-controlled reclaim, arbitrary write, controlled object replacement, or a practical LPE chain. It should still not be auto-closed because TX completion cleanup-path bugs in network drivers can hide real lifetime corruption. ## 5. One-sentence report phrase A stale TX buffer type in the Intel igc SMD frame path can cause TX completion to use an XDP or XSK cleanup path for an SKB-backed buffer, creating a plausible wrong-free or lifetime-corruption condition with local DoS impact and possible higher impact requiring manual review. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: the patch directly fixes a stale type field that controls cleanup behavior for reused TX buffer entries. Even though exploitation is configuration dependent and not remotely reachable, wrong cleanup paths involving SKB/XDP/XSK ownership are lifetime-sensitive and can plausibly become UAF or type confusion. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: igc: set tx buffer type for SMD frames [ Upstream Commit: 1f83545f432d106d5fc71d3997b2d382104ebcc4 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1f83545f432d106d5fc71d3997b2d382104ebcc4 Changed files: drivers/net/ethernet/intel/igc/igc_tsn.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=1f83545f432d106d5fc71d3997b2d382104ebcc4 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64035 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64035 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:H/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 7 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: 3 Paranoid ActionableScore: 6 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).