From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-64175][LOW] wifi: iwlwifi: mld: stop TX during firmware restart Date: Sun, 19 Jul 2026 15:02:36 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-64175 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 2 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: dc31c69476520bb4c2a208211a8d3c310a62c4d0 List-Id: CVE: CVE-2026-64175 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: wifi: iwlwifi: mld: stop TX during firmware restart Commit: dc31c69476520bb4c2a208211a8d3c310a62c4d0 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dc31c69476520bb4c2a208211a8d3c310a62c4d0 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64175 Analysis date: Sun, 19 Jul 2026 15:02:36 -0400 ActionableScore: 2 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: iwlwifi MLD could continue dequeuing and freeing TX skbs during firmware restart, causing CPU churn and memory pressure under sustained traffic, but the issue appears limited to local or workload-assisted denial of service without memory corruption or privilege escalation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64175 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64175 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: LOW Manual review required: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-64175 LOW 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:N/I:N/A:H';**CWE-400;CWE-703;CWE-754;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'iwlwifi mld TX can continue dequeuing frames while firmware restart is in progress after a firmware crash. Each dequeued skb is passed to the transport even though firmware is dead, so iwl_trans_tx returns EIO and the skb is immediately freed, creating CPU churn and slab allocation pressure under high throughput workloads. For the CVSS the PR:L is used because reliable triggering normally requires a local user or process workload that can generate sustained TX traffic while the device is in firmware restart. The issue is not directly network reachable as a packet parsing flaw, although remote traffic can contribute to the workload in deployments where the host sends traffic over the affected WiFi device. Impact is denial of service or degraded availability only, with no evidence of UAF, OOB access, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) YES REMOTE DANGER UAF NETWORK SKB KERNEL_PANIC_PLUS_UAF HARDWARE LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ## 1. ActionableScore * Conservative score: **2** * Paranoid score: **2** * Final recommended bucket: **Ordinary Moderate / Low-like** ## 2. Signal breakdown Triggered signals: * **Local unprivileged trigger: +1** A local unprivileged process can generate sustained TX traffic, for example UDP or SSH traffic, while the device is in firmware restart. * **Firmware-mediated external influence: +1** The problematic state depends on an iwlwifi firmware crash and restart. External wireless conditions or traffic may contribute, but this is not a directly remote packet-parsing vulnerability. * **Availability impact realistic: +1** The bug can cause CPU churn and skb allocation churn, leading to memory pressure and degraded availability under high-throughput restart scenarios. Subtracted signals: * **Hard or unreliable condition: -1** Reliable triggering requires a firmware crash or restart window plus sustained TX traffic. This is not a simple always-available local trigger. Not awarded: * **Remote reachable / network-triggerable: +0** Remote traffic may contribute to workload, but the bug is not directly triggered by parsing attacker-controlled network packets. * **Generic memory corruption: +0** No UAF, double free, OOB write, heap overwrite, refcount misuse, or type confusion is shown. * **Privilege escalation plausible: +0** The patch and described behavior only support resource pressure / DoS. * **Reliable kernel crash / strong DoS: +0** The described effect is CPU and memory pressure from allocation churn, not a direct kernel panic or deterministic crash. ## 3. Reachability analysis A local process can help trigger the condition by generating sustained outbound traffic while the affected iwlwifi device is in firmware restart. The firmware crash itself is a required precondition and may be hardware or firmware specific. Remote peers can contribute to traffic patterns, but they do not appear to have a direct protocol-level trigger for the kernel bug. Namespaces and containers do not materially improve reachability unless the container can drive traffic through the affected WiFi interface. No CAP_SYS_ADMIN or CAP_NET_ADMIN appears necessary merely to generate traffic, but reliable reproduction depends on the firmware restart state. The path is limited to the iwlwifi MLD sub-driver and affected Intel WiFi 7 style deployments, so it is not a broad core networking exposure. ## 4. Severity interpretation This behaves like an **ordinary Moderate / Low-like resource pressure issue**, not an Important-class vulnerability. The realistic impact is degraded availability from CPU churn and skb allocation pressure during firmware restart. There is no evidence of memory corruption, privilege escalation, confidentiality impact, or integrity impact. The theoretical worst case remains DoS/resource exhaustion. It should not be elevated to Actionable Moderate or Important based on the provided patch. ## 5. One-sentence report phrase iwlwifi MLD could continue dequeuing and freeing TX skbs during firmware restart, causing CPU churn and memory pressure under sustained traffic, but the issue appears limited to local or workload-assisted denial of service without memory corruption or privilege escalation. ## 6. Manual review recommendation **NO MANUAL CHECK NEEDED** This is a resource pressure / DoS-only issue with no demonstrated memory corruption primitive, no security-boundary bypass, and no direct remote trigger. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: wifi: iwlwifi: mld: stop TX during firmware restart Commit: dc31c69476520bb4c2a208211a8d3c310a62c4d0 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dc31c69476520bb4c2a208211a8d3c310a62c4d0 Commit description: When iwlwifi firmware crashes (e.g., NMI_INTERRUPT_UNKNOWN on Intel BE201/Wi-Fi 7), iwl_mld_nic_error() sets mld->fw_status.in_hw_restart to true. However, iwl_mld_tx_from_txq() does not check this flag before dequeuing frames from mac80211 and pushing them to the transport layer. Since the firmware is dead, iwl_trans_tx() returns -EIO for each frame, which then gets freed immediately. Under high-throughput conditions (e.g., Tailscale UDP traffic or active SSH sessions), this creates a tight dequeue-send-fail-free loop that wastes CPU cycles and generates rapid skb allocation churn, leading to memory pressure from slab fragmentation. The RX path already has this guard (iwl_mld_rx_mpdu checks in_hw_restart at rx.c:1906), and so does the TXQ allocation worker (iwl_mld_add_txqs_wk at tx.c:156). Add the same guard to iwl_mld_tx_from_txq() to stop all TX during firmware restart. Frames left in mac80211's TXQs are naturally drained after restart completes, when queue reallocation triggers iwl_mld_tx_from_txq() via iwl_mld_add_txq_list(), or when new upper-layer traffic invokes wake_tx_queue. Tested on ASUS Zenbook 14 UX3405CA with Intel BE201 (Wi-Fi 7) on kernel 6.19.5 where the firmware crashes approximately every 10-15 minutes under Tailscale traffic. Fixes: d1e879e ("wifi: iwlwifi: add iwlmld sub-driver") Cc: stable@vger.kernel.org Signed-off-by: Sheroz Juraev Link: https://patch.msgid.link/20260315081221.2678478-1-goodmartiandev@gmail.com Signed-off-by: Miri Korenblit Signed-off-by: Greg Kroah-Hartman Changed files: drivers/net/wireless/intel/iwlwifi/mld/tx.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=dc31c69476520bb4c2a208211a8d3c310a62c4d0 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64175 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64175 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:N/I:N/A:H The Best / paranoid CVSS score: 4.7 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: unknown Paranoid ActionableScore: 2 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: LOW KPANIC detected for this report: NO Published priority for this report (same as in Subject): LOW 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).