From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-74336][MODERATE REGULAR] wifi: mac80211: bound S1G TIM PVB walk to the TIM element [ Upstream Date: Sat, 15 Aug 2026 13:09:43 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-74336 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 4 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: 3abc13ec3ac28c343ad7e7b7496e807b924f0edd List-Id: CVE: CVE-2026-74336 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: wifi: mac80211: bound S1G TIM PVB walk to the TIM element [ Upstream Commit: 3abc13ec3ac28c343ad7e7b7496e807b924f0edd Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3abc13ec3ac28c343ad7e7b7496e807b924f0edd Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74336 Analysis date: Sat, 15 Aug 2026 13:09:43 -0400 ActionableScore: 4 ActionableScore lower bound: 3 Actionable bucket: Borderline, manual review recommended / Actionable Moderate watchlist Manual review required: YES Summary: A nearby wireless attacker may trigger a bounded out-of-bounds read in the mac80211 S1G TIM parser by causing the PVB walker to read up to two bytes past the TIM element, with limited confidentiality concern and possible DoS but no demonstrated privilege escalation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74336 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74336 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 REGULAR 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-2026-74336 MODERATE CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H';CWE-125;CWE-126;*CWE-20;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '7.1';DESCR 'An out of bounds read in the mac80211 S1G TIM parser can occur because ieee80211_s1g_check_tim() passes an end pointer two bytes beyond the TIM payload to the PVB block walker. A nearby attacker in wireless range could craft an S1G TIM element so the parser reads adjacent skb or heap bytes when the TIM element is at the end of the frame. For the CVSS the PR:N is used for the paranoid score because triggering does not require local credentials on the victim and only requires adjacent wireless reachability to a vulnerable S1G receive path. The attack is not Internet reachable and should be treated as AV:A rather than AV:N because it depends on local WiFi radio proximity. Impact is at least a limited confidentiality concern from adjacent kernel buffer reads and in worst case may cause denial of service if the invalid read reaches an unmapped or hardened memory boundary. YES REQUIRES MANUAL CHECK.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended / Actionable Moderate watchlist (with actual score 4) SKIP CVE-2026-74336 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE OOB SIMPLEFIX DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: 3 * Paranoid score: 4 * Final recommended bucket: **Borderline, manual review recommended / Actionable Moderate watchlist** ## 2. Signal breakdown Conservative signals: * Remote reachable / network-triggerable: +2 The bug is triggered by received WiFi S1G management/TIM parsing. It is not Internet-reachable, but it is adjacent-network reachable by a nearby radio attacker. * Confidentiality impact plausible: +1 The primitive is a bounded out-of-bounds read of up to two bytes from adjacent skb/heap data. Direct disclosure is not demonstrated, but limited parser-observable data influence is plausible. * Rare AND difficult-to-reach subsystem/configuration: -1 S1G / 802.11ah is much less common than ordinary WiFi paths and requires a vulnerable S1G receive path. Paranoid additional signal: * Availability impact realistic: +1 Not proven as a reliable crash, but malformed frame parsing plus OOB read in kernel receive path can justify limited DoS concern for manual triage, especially with hardened/debug builds or boundary-sensitive layouts. Not awarded: * Generic memory corruption: +0 This is read-only OOB, not UAF, double-free, OOB write, type confusion, or arbitrary write. * Privilege escalation plausible: +0 No reclaim, overwrite, callback, refcount takeover, or writable stale object primitive is shown. * Strong DoS: +0 conservative The patch describes OOB read, not a demonstrated panic or reliable crash. ## 3. Reachability analysis A nearby attacker in wireless range could potentially trigger the bug by sending a crafted S1G TIM element that reaches the mac80211 S1G parser. No local account or victim-side privileges are required, so this is closer to PR:N in CVSS terms. The path is adjacent-network only, not AV:N Internet-reachable, and practical exposure depends on S1G support and whether the affected receive path is enabled on the target device. Containers and namespaces do not materially change reachability because the trigger is external wireless frame parsing, not a local userspace API. Call-site confidence: medium. The patch and commit message identify the parser input, the incorrect end pointer, and the downstream walker behavior, but not a demonstrated external disclosure channel or production crash. ## 4. Severity interpretation This behaves more like an actionable Moderate / manual-review candidate than a Strong Important issue. The theoretical concern is kernel adjacent-buffer OOB read from a network-adjacent parser, which should not be auto-dismissed. Realistic exploitation evidence is limited because the read is only up to two bytes, read-only, and no direct leak, write primitive, UAF, or privilege escalation path is shown. ## 5. One-sentence report phrase A nearby wireless attacker may trigger a bounded out-of-bounds read in the mac80211 S1G TIM parser by causing the PVB walker to read up to two bytes past the TIM element, with limited confidentiality concern and possible DoS but no demonstrated privilege escalation. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: adjacent-network reachable OOB read in a kernel packet parser, but limited to read-only access with no demonstrated leak channel, crash reliability, or LPE primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: wifi: mac80211: bound S1G TIM PVB walk to the TIM element [ Upstream Commit: 3abc13ec3ac28c343ad7e7b7496e807b924f0edd Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3abc13ec3ac28c343ad7e7b7496e807b924f0edd Changed files: net/mac80211/parse.c include/linux/ieee80211-s1g.h 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=3abc13ec3ac28c343ad7e7b7496e807b924f0edd ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74336 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74336 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:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H The Best / paranoid CVSS score: 7.1 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: 4 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: NO Published priority for this report (same as in Subject): MODERATE REGULAR 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).