From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98423][LOW] wifi: mac80211_hwsim: don't hand frames to mac80211 while stopping [ Upstream Date: Sun, 25 Oct 2026 20:59:02 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98423 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: 1 X-AL-KERNEL-ActionableScore-Lower: 0 X-AL-KERNEL-Commit: 5ce9b2bc9e73213e316a8c72400256a76bf41814 List-Id: CVE: CVE-2026-98423 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: wifi: mac80211_hwsim: don't hand frames to mac80211 while stopping [ Upstream Commit: 5ce9b2bc9e73213e316a8c72400256a76bf41814 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5ce9b2bc9e73213e316a8c72400256a76bf41814 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98423 Analysis date: Sun, 25 Oct 2026 20:59:02 -0400 ActionableScore: 1 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A local wmediumd race can deliver a frame after hwsim radio shutdown, causing a mac80211 WARN and a conditional panic when `panic_on_warn` is enabled. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98423 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98423 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-2026-98423 LOW https://www.kernelcve.org/list/?q=CVE-2026-98423 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=LOW RESULT=DIFF TEMP_DISTANCE_MERGE_SKIP=AEGIS_NO_POSITIVE_SEVERITY_EVIDENCE (final Legacy and Aegis differ; FINAL: LOW, Aegis: 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:N/I:N/A:H';CWE-362;CWE-367;CWE-667;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A race in mac80211_hwsim allows a frame received from the local wmediumd userspace path to pass the started check before the virtual radio is stopped and then reach mac80211 after shutdown. This triggers WARN_ON when mac80211 observes that the hardware is not started. No UAF, OOB access, or other memory corruption primitive is shown by the affected path. For the CVSS the PR:L value reflects that a local process must be able to use the mac80211_hwsim userspace frame interface. AC:H reflects the need to win the timing window between the started check and radio shutdown. Normal impact is limited to a kernel warning, while systems configured with panic_on_warn may experience a kernel panic and host denial of service. The issue is not directly network reachable because an over the air or ordinary remote WiFi frame does not by itself provide access to the wmediumd control path. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. 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 LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic and 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_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 2.0 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE REMOTE LOCK DANGER VIRT ERRORPATH NETWORK SKB SYZBOT DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 ActionableScoreLower=0 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 0. * Conservative score: 0; no floor or cap applied. * Raw paranoid score: 1. * Paranoid score: 1; conditional panic-on-WARN supports a possible host crash. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * Base +0 — the race hands a frame to mac80211 after `data2->started` becomes false, reaching `WARN_ON(!local->started)`. WARN-only behavior scores zero absent a fatal consequence. * Paranoid +1 — systems configured with `panic_on_warn` can convert this specific warning into a host kernel panic. * No UAF, OOB access/write, refcount mutation, stale-object consumption, or other memory-corruption primitive is shown. * No authorization decision changes from DENY to ALLOW; B4-PENDING does not apply. * No extra availability point: the possible panic is the only availability effect. * No race penalty applied: the window exists, but the evidence does not quantify it as sufficiently narrow or uncontrollable for a scoring subtraction. * No local-unprivileged bonus: access to the complete wmediumd frame-injection plus radio-stop sequence is not established for a normal user. * NEW52 B5-R and NEW53 B3-PENDING do not apply: there is neither an OOB write nor a shared-backing write. 3. Reachability analysis The vulnerable input comes from the local wmediumd userspace/netlink path, not ordinary over-the-air traffic. Triggering requires frame delivery to race with virtual-radio shutdown. The supplied evidence does not resolve which credentials control the complete sequence, whether all required operations are namespace-scoped, or whether prior privileged hwsim/wmediumd setup is required. No special physical hardware is needed because hwsim is virtual. 4. Primitive and severity reading The exact defect is a check-to-use synchronization race on active radio state. The fix holds `data2->mutex` from the `started` check through `mac80211_hwsim_rx()` and synchronizes stop-side state transition with the same mutex. The shown outcome is an invalid-state delivery and WARN, classified CLASS_C. A panic is configuration-dependent; memory corruption, information disclosure, integrity compromise, and privilege escalation are unsupported. Therefore this is not an Important candidate and may be automatically downgraded. 5. One-sentence report phrase A local wmediumd race can deliver a frame after hwsim radio shutdown, causing a mac80211 WARN and a conditional panic when `panic_on_warn` is enabled. 6. Manual review advice NO MANUAL CHECK NEEDED The patch and call path show a synchronization/WARN defect without a separate corruption or security-boundary primitive. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: wifi: mac80211_hwsim: don't hand frames to mac80211 while stopping [ Upstream Commit: 5ce9b2bc9e73213e316a8c72400256a76bf41814 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5ce9b2bc9e73213e316a8c72400256a76bf41814 Changed files: drivers/net/wireless/mac80211_hwsim.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=5ce9b2bc9e73213e316a8c72400256a76bf41814 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98423 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98423 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: 0 Paranoid ActionableScore: 1 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).