From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-52984][LOW] net/sched: netem: fix queue limit check to include reordered packets [ Upstream Date: Wed, 24 Jun 2026 14:02:23 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-52984 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: 0 X-AL-KERNEL-Commit: 0f875d52db4c921da610e481b72f03cc82fdcb72 List-Id: CVE: CVE-2026-52984 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: net/sched: netem: fix queue limit check to include reordered packets [ Upstream Commit: 0f875d52db4c921da610e481b72f03cc82fdcb72 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0f875d52db4c921da610e481b72f03cc82fdcb72 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52984 Analysis date: Wed, 24 Jun 2026 14:02:23 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like, auto-close candidate Manual review required: NO Summary: A netem queue accounting bug can miss reordered packets in the qdisc queue, allowing total occupancy to exceed the configured limit under sustained traffic and causing a configuration-dependent DoS without evidence of memory corruption or privilege escalation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-52984 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52984 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-2026-52984 LOW CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';CWE-770;**CWE-400;CWE-682;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'netem queue limiting can be bypassed when packet reordering is enabled because the enqueue limit check counted only the internal tfifo length and missed packets already placed on the qdisc queue by the reorder path. Under sustained traffic this can allow total queued packets to exceed the configured sch limit and may consume more kernel networking memory than intended, causing local or path scoped denial of service. For the CVSS the PR:N is used for the paranoid network path because a traffic sender does not need privileges on the target once a vulnerable netem qdisc with reordering is already configured. The issue is not a memory corruption bug and does not provide a direct confidentiality or integrity primitive. Network reachability is limited to traffic that traverses the affected qdisc, so practical exploitation usually requires an internal test, lab, router, or traffic shaping environment using netem reordering.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like, auto-close candidate (with actual score 1) YES REMOTE SIMPLEFIX NETWORK LINUS QDISC PACKET DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like, auto-close candidate** ## 2. Signal breakdown Conservative signals: * Availability impact realistic: +1. The queue limit accounting bug can allow netem queue occupancy to exceed the configured limit and may cause memory pressure or packet queuing DoS. * Requires admin/root/CAP_NET_ADMIN in typical deployments: -2. Configuring netem qdisc and reordering normally requires CAP_NET_ADMIN. * Rare AND difficult-to-reach subsystem/configuration: -1. The vulnerable behavior requires netem with reordering enabled, which is not a default production networking path. * Conservative score is floored to 0. Paranoid signals: * Remote reachable / network-triggerable: +2. If a vulnerable netem qdisc with reordering is already configured on a forwarding or shaping path, a traffic sender may trigger excessive queue growth without local privileges on the target. * Availability impact realistic: +1. Sustained traffic through the affected qdisc can exceed the intended queue limit and cause resource exhaustion. * Rare AND difficult-to-reach subsystem/configuration: -1. Exploitation depends on a specific traffic-control setup with netem reordering. * No memory corruption signal. The patch fixes queue accounting only, with no UAF, OOB write, double free, object lifetime issue, or attacker-controlled overwrite. * No confidentiality or integrity signal. The impact is limited to resource exhaustion / DoS. ## 3. Reachability analysis In the conservative model, the attacker must be able to configure or control the netem qdisc, which normally requires CAP_NET_ADMIN. In delegated network namespaces or containers, the practical privilege requirement may be lower for that namespace, but the impact is usually scoped to the configured traffic path. In the paranoid model, netem with reordering is already configured by an administrator on a host, router, lab system, CI environment, or traffic-shaping node. A remote or adjacent sender whose packets traverse that qdisc may increase queue occupancy beyond the intended limit. This is not a general Internet-reachable kernel path and is not enabled by default. ## 4. Severity interpretation This behaves like an ordinary Moderate / Low-like resource accounting bug rather than an Important-class vulnerability. The realistic impact is denial of service through excessive queue growth or memory pressure under a specific netem reordering configuration. There is no evidence of memory corruption, privilege escalation, information disclosure, or persistent integrity impact. ## 5. One-sentence report phrase A netem queue accounting bug can miss reordered packets in the qdisc queue, allowing total occupancy to exceed the configured limit under sustained traffic and causing a configuration-dependent DoS without evidence of memory corruption or privilege escalation. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can be auto-closed for urgent security triage because it is a resource accounting / queue limit issue with configuration-dependent reachability, no concrete memory corruption primitive, and no plausible LPE or confidentiality impact. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net/sched: netem: fix queue limit check to include reordered packets [ Upstream Commit: 0f875d52db4c921da610e481b72f03cc82fdcb72 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0f875d52db4c921da610e481b72f03cc82fdcb72 Changed files: net/sched/sch_netem.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=0f875d52db4c921da610e481b72f03cc82fdcb72 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-52984 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52984 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:L/PR:H/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 5.3 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: 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).