From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98384][MODERATE REGULAR] bpf: Fix out-of-bounds read of sk_protocol in bpf_sock_destroy() [ Upstream Date: Fri, 09 Oct 2026 22:21:54 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98384 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: 2 X-AL-KERNEL-ActionableScore-Lower: 1 X-AL-KERNEL-Commit: 5b4eb82475ae17d55974235c09e97044829426a8 List-Id: CVE: CVE-2026-98384 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: bpf: Fix out-of-bounds read of sk_protocol in bpf_sock_destroy() [ Upstream Commit: 5b4eb82475ae17d55974235c09e97044829426a8 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5b4eb82475ae17d55974235c09e97044829426a8 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98384 Analysis date: Fri, 09 Oct 2026 22:21:54 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98384 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98384 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-98384 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98384 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE AEGIS_AS=1 LEGACY=MODERATE RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both MODERATE) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-125;CWE-704;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'bpf_sock_destroy can receive a TIME_WAIT or request socket from the TCP BPF iterator even though sk_protocol exists only in a full struct sock. Reading sk_protocol from either smaller object causes a two byte slab out of bounds read and can trigger a KASAN warning or a kernel crash when panic on warning behavior is enabled. For the CVSS the PR:L value is used for the paranoid score because a user with delegated BPF capabilities or access through a BPF service account may trigger the affected iterator path without having unrestricted root control. The issue is not directly network reachable because an attacker must execute a local BPF program and invoke the kfunc on a socket returned by the iterator. Impact is primarily local denial of service. The demonstrated invalid read does not provide a direct information disclosure, controlled write, UAF, or established privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) MAYBE REMOTE READ KASAN OOB BPF TEST - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 2 * Paranoid score: 2 * No floor or cap changed either score. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown Conservative signals: * +1 Weak corruption concern. `bpf_sock_destroy()` performs a confirmed two-byte slab out-of-bounds read when a TIME_WAIT or request socket is interpreted as a full `struct sock`. * +0 Reliable crash. The supplied trace demonstrates a KASAN warning, not an unconditional production-kernel panic. * +0 Confidentiality. The incorrectly read bytes are used in a protocol comparison and are not returned to userspace or another observable output. * +0 Integrity. No write, UAF, refcount mutation, object corruption, or authorization bypass is established. * +0 Local unprivileged trigger. Loading the required BPF program and invoking this kfunc below host-admin privilege is not established. * +0 Privilege penalty. The complete BPF privilege boundary is unresolved, so no unsupported host-admin penalty is applied. Paranoid addition: * +1 Strong DoS possibility. A kernel configured to panic on KASAN or warning conditions can convert the demonstrated invalid read into a host crash. Important non-awarded signals: * NEW52 B5-R does not apply because this is an OOB read, not a retry-accumulated heap OOB write. * NEW53 B3-PENDING does not apply because no write to shared or file-backed storage exists. * NEW54 B4-PENDING does not apply because no authorization decision changes from DENY to ALLOW. * Controlled reclaim, arbitrary write, disclosure, UAF, LPE, and remote reachability are not demonstrated. * No extra Availability point is awarded for the same possible panic. * BPF object complexity does not create an exploitation-leverage bonus. 3. Reachability analysis The demonstrated path requires a BPF program using the TCP iterator to pass a TIME_WAIT or request socket to `bpf_sock_destroy()`. The input establishes the kernel call path but does not establish the complete load and execution permissions for the evaluated system. BPF loading and kfunc use are commonly privilege-gated, but the evidence does not prove either full host-admin requirements or a complete below-host-admin delegated path. Therefore, `HostAdminRequired` and `NamespaceScopedPrivilege` remain `UNKNOWN`. The mere possibility of delegated `CAP_BPF` or a BPF service account is insufficient to prove below-host-admin reachability. The issue is not directly network-triggerable. Network activity can create relevant TCP socket states, but an attacker must also execute the required local BPF iterator program. No special hardware, race, retry sequence, or namespace-complete trigger is established. 4. Primitive and severity interpretation The exact primitive is a bounded two-byte slab out-of-bounds read caused by accessing `sk_protocol`, which exists in a full `struct sock`, through an object that may instead be a TIME_WAIT or request socket. This is neither a UAF nor stale lifetime use. It is an invalid structured-object read with a limited control-flow effect on the protocol check. The later operation does not consume attacker-controlled corrupted state because no state is written or corrupted. `PrimitiveClass=CLASS_C` is appropriate because the demonstrated effect is an invalid read and KASAN warning, with possible configuration-dependent DoS but no independently useful corruption primitive. `ImportantCandidate=NO` follows from the absence of write, disclosure, ownership violation, authorization bypass, or exploitation leverage beyond the warning or crash. `AutoDowngradeAllowed=YES` is appropriate, although manual review remains recommended because the defect is a real kernel slab OOB access in a BPF-reachable path. Likely operational severity is Low to ordinary Moderate. 5. One-sentence report phrase A BPF TCP iterator can pass a TIME_WAIT or request socket to bpf_sock_destroy, causing a two-byte slab out-of-bounds read of sk_protocol and a KASAN warning or configuration-dependent kernel DoS without a demonstrated disclosure, write, UAF, or privilege-escalation primitive. 6. Manual review recommendation MANUAL CHECK RECOMMENDED The kernel OOB read is concrete, but current evidence supports only constrained invalid-read and possible DoS impact, while exact BPF privilege requirements remain unresolved. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: bpf: Fix out-of-bounds read of sk_protocol in bpf_sock_destroy() [ Upstream Commit: 5b4eb82475ae17d55974235c09e97044829426a8 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5b4eb82475ae17d55974235c09e97044829426a8 Changed files: net/core/filter.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=5b4eb82475ae17d55974235c09e97044829426a8 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98384 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98384 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:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 5.5 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: 1 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: 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).