From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98168][MODERATE REGULAR] smb: client: fix reparse buffer bounds in cifs_query_reparse_point() [ Upstream Date: Tue, 06 Oct 2026 14:56:27 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98168 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: 3d67f155fe5813cfb02a551a9a12d6ea06a902e9 List-Id: CVE: CVE-2026-98168 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: smb: client: fix reparse buffer bounds in cifs_query_reparse_point() [ Upstream Commit: 3d67f155fe5813cfb02a551a9a12d6ea06a902e9 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3d67f155fe5813cfb02a551a9a12d6ea06a902e9 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98168 Analysis date: Tue, 06 Oct 2026 14:56:27 -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-2026-98168 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98168 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-2026-98168 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98168 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H';CWE-125;*CWE-20;CWE-1284;Other CVSS 'AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H';BEST CVSS score: '8.2';DESCR 'The SMB1 client validates that DataOffset points inside the response but does not verify that enough bytes remain for the fixed 8-byte reparse_data_buffer header. A malicious or compromised SMB server can return a crafted reparse point response with fewer than 8 bytes after the selected offset. Subsequent reads of ReparseTag and ReparseDataLength then occur outside the logical response boundary and may cause a kernel warning, invalid response processing, or a kernel crash. For the CVSS the PR:N value is used because the attacking server does not need local privileges on the client. The base score uses UI:R because the client normally has to connect to or access the SMB share and request the reparse point. The paranoid score uses UI:N because an existing mount, automount, or background client operation may issue the request without a new user action. The issue is network reachable but normally requires SMB1 to be enabled and the client to communicate with an attacker controlled or compromised SMB server. Impact is at least denial of service. A limited confidentiality impact is retained for manual review because the primitive is an out of bounds read, although direct disclosure of the read data is not demonstrated.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) MAYBE OOB DISK SIMPLEFIX ERRORPATH IMPROVEONLY SERVERTOCLIENT LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 2 * Paranoid score: 2 * No floor or cap was applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown Conservative signals: * +2 Remote server-controlled input. A malicious or compromised SMB server controls `DataOffset` and the truncated reparse response consumed by the kernel client. * -1 Legacy/non-default execution mode. The vulnerable function processes SMB1 responses, while modern CIFS mounts normally negotiate newer SMB dialects. * +0 Limited OOB read. The established primitive is an internal read beyond the logical response boundary, without a disclosure path, write, UAF, or control-flow primitive. * +0 Kernel crash. The patch establishes an OOB read but does not demonstrate that it crosses the backing allocation or reliably crashes a production kernel. Raw conservative score: `2 - 1 = 1`. Paranoid difference: * +1 Plausible kernel crash/DoS. If the short response ends at an allocation or protected boundary, the header-field reads may fault or trigger a fatal memory-safety check. Raw paranoid score: `2 + 1 - 1 = 2`. Not awarded: * Confidentiality was not awarded because no bytes are shown being returned to userspace or the server. * Integrity was not awarded because there is no OOB write or security-sensitive state modification. * Strong or weak exploitation leverage was not awarded because the malformed fields only establish a bounded invalid read. * No extra Availability point was awarded because it would duplicate the possible kernel crash. * No UAF, controlled reclaim, type confusion, arbitrary write, or privilege-escalation path is established. * No separate local-unprivileged point was awarded because the scored attacker is the remote SMB server, and local access only initiates the client request. 3. Reachability analysis A malicious or compromised SMB1 server can construct the response. The attacker requires no local account, capability, or host-administrator privilege on the client. The client must already use an SMB1 mount and issue a query-reparse-point request. Creating a kernel CIFS mount commonly involves prior administrative setup, but after the mount exists, ordinary filesystem activity may cause the client to issue the request. This prerequisite is reflected through the SMB1 legacy-mode reduction rather than an unsupported attacker privilege penalty. No namespace capability is part of the demonstrated trigger. No special hardware or race is required. Triggering depends on protocol sequencing and a crafted server response, not timing. 4. Primitive and severity interpretation The exact primitive is a bounded OOB read from a server-supplied SMB1 response. When fewer than eight bytes remain after `DataOffset`, the client casts that location to `struct reparse_data_buffer` and reads fixed header fields beyond the logical response. This is not a UAF, ownership violation, or active structured-object lifetime bug. It is CLASS_C because the demonstrated behavior is malformed-response processing with possible warning or crash, without an independently useful corruption primitive. The patch-supported practical consequence is an invalid kernel read. Kernel DoS is technically plausible but not shown to be reliable. Information disclosure and privilege escalation remain unsupported because no read-back or state-modification path is supplied. `ImportantCandidate=NO` because neither Class A nor meaningful Class B leverage exists. `AutoDowngradeAllowed=YES` because the issue is a constrained SMB1 OOB read without disclosure, write, lifetime corruption, or unresolved security-boundary primitive. Likely operational severity is ordinary Moderate or Low-like, with higher priority only for systems that still mount SMB1 shares from untrusted or compromise-prone servers. 5. One-sentence report phrase A malicious SMB1 server can return a truncated reparse-point response that causes the Linux CIFS client to read beyond the logical response boundary, with a possible but unproven kernel crash and no demonstrated disclosure or write primitive. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Confirm whether the affected reads can cross the actual allocation boundary or influence subsequent parsing in a way that creates disclosure or a stronger memory-access primitive. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: smb: client: fix reparse buffer bounds in cifs_query_reparse_point() [ Upstream Commit: 3d67f155fe5813cfb02a551a9a12d6ea06a902e9 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3d67f155fe5813cfb02a551a9a12d6ea06a902e9 Changed files: fs/smb/client/cifssmb.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=3d67f155fe5813cfb02a551a9a12d6ea06a902e9 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98168 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98168 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:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H The Best / paranoid CVSS score: 8.2 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).