From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98797][MODERATE 7.0] net: cap skb->queue_mapping when the tx queue is picked [ Upstream Date: Sat, 24 Oct 2026 06:12:49 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98797 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: unknown X-AL-KERNEL-Commit: c6ec35c8267c84c2094cb485db20c06384fc2bcc List-Id: CVE: CVE-2026-98797 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: net: cap skb->queue_mapping when the tx queue is picked [ Upstream Commit: c6ec35c8267c84c2094cb485db20c06384fc2bcc Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c6ec35c8267c84c2094cb485db20c06384fc2bcc Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98797 Analysis date: Sat, 24 Oct 2026 06:12:49 -0400 ActionableScore: 5 ActionableScore lower bound: unknown Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review Manual review required: YES Summary: A namespace-local CAP_NET_ADMIN user can induce an OOB taprio child-pointer read that is consumed as an active Qdisc pointer and can panic the host kernel. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98797 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98797 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-2026-98797 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98797 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 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:H/I:H/A:H';CWE-125;CWE-129;*CWE-20;CWE-822;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A nested tc egress transmission can leak skip_txqueue state into an outer __dev_queue_xmit call, allowing a stale skb queue mapping from a device with more queues to index beyond the taprio qdiscs array on a device with fewer queues. The confirmed primitive is an out of bounds pointer read followed by use of the result as a struct Qdisc pointer, which produces a KASAN slab out of bounds fault and can panic the kernel. For the CVSS the PR:L value reflects that reliable triggering requires a local user or process with CAP_NET_ADMIN in a network namespace and control of qdisc and tc action configuration. AC:H reflects the required nested redirect or mirror ordering and multi device queue layout. The base impact is local denial of service. In the paranoid case the invalid Qdisc pointer use leaves a plausible but unproven path to controlled kernel memory access or control flow if adjacent heap contents can be influenced, so privilege escalation requires further manual validation. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 7 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 LOW to MODERATE_KPANIC because the manual review requirement 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 INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 with primitive class CLASS_C 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 WRITE KASAN OOB BPF NETFILTER SKB HARDWARE LINUS QDISC PACKET KPANIC INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 PrimitiveClass=CLASS_B RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=YES ImportantCandidate=YES ManualReview=REQUIRED AutoDowngradeAllowed=NO RequiresHostUID0=NO AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 5. * Conservative score: 5; no floor or cap applied. * Raw paranoid score: 5. * Paranoid score: 5; stronger memory-corruption effects are not sufficiently proven. * Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**:: 2. Signal breakdown * +1 weak/indirect corruption: attacker-influenced stale `queue_mapping` indexes beyond `taprio`’s allocated `q->qdiscs[]`, and the resulting value is treated as a `struct Qdisc *`. * +1 reliable kernel crash: the supplied namespace reproducer consistently produces a KASAN slab-OOB fault and can panic with `panic_on_warn=1`. * +1 local unprivileged trigger: the commit expressly grounds the complete reproducer in a local user obtaining `CAP_NET_ADMIN` inside a network namespace. * +1 high-control data-plane API: that actor configures queue counts, `skbedit` queue mappings, taprio, and nested mirred transmissions that determine the invalid index. * +1 packet-processing exposure: the invalid pointer selection occurs in the transmit/qdisc path and is consumed during packet enqueue. * No timing penalty: this is a reproducible nested-call ordering, not a demonstrated narrow or unreliable race. * No privilege penalty: the complete demonstrated trigger is namespace-scoped rather than host-administrator-equivalent. * No OOB-write, controlled adjacent contents, controlled type confusion, arbitrary write, disclosure, UAF, or LPE is shown. The confirmed initial access is an OOB pointer read followed by structured-pointer consumption. * NEW52/B5-R does not apply: there is no confirmed heap OOB write or retry-accumulated index. * No extra availability point is awarded for the same panic. * No confidentiality or integrity impact is awarded from the speculative possibility of useful adjacent heap contents. 3. Reachability analysis The demonstrated actor is a local user with `CAP_NET_ADMIN` in an attacker-controlled network namespace. The supplied reproducer shows that this authority suffices for dummy-device creation, qdisc/action setup, queue-mapping selection, and packet transmission; host UID 0 and host administrative capability are not required. No special hardware, eBPF program, prior host provisioning, or timing race is required. The multi-device/taprio/mirred configuration raises complexity but is repeatable and attacker-controlled. 4. Primitive and severity reading The primitive is an attacker-selected OOB array index that loads memory beyond `q->qdiscs[]` and consumes the result as an active `Qdisc` pointer. This is not a UAF or confirmed write, so it remains CLASS_B rather than CLASS_A. The proven effect is a host-kernel fault from a network-namespace-controlled operation. Useful adjacent-object interpretation, callback influence, or non-crash host-state corruption remains unproven. ImportantCandidate is YES because an attacker-influenced bogus active-object pointer reaches privileged qdisc processing across the namespace/host-kernel trust boundary, while consequences beyond the demonstrated panic remain unresolved. Auto-downgrade is disallowed pending examination of the exact `qdisc_enqueue()` consumption and feasible adjacent slab objects. 5. One-sentence report phrase A namespace-local CAP_NET_ADMIN user can induce an OOB taprio child-pointer read that is consumed as an active Qdisc pointer and can panic the host kernel. 6. Manual review advice MANUAL CHECK REQUIRED Review adjacent allocation types and the subsequent Qdisc field/callback consumption; neither an exploitable non-crash primitive nor harmless crash-only containment is established. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net: cap skb->queue_mapping when the tx queue is picked [ Upstream Commit: c6ec35c8267c84c2094cb485db20c06384fc2bcc Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c6ec35c8267c84c2094cb485db20c06384fc2bcc Changed files: include/linux/netfilter_netdev.h include/linux/rtnetlink.h include/linux/skbuff.h include/net/sch_generic.h net/core/dev.c net/sched/act_skbedit.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=c6ec35c8267c84c2094cb485db20c06384fc2bcc ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98797 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98797 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: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: unknown 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).