From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98170][MODERATE REGULAR] smb: client: fix OOB struct field reads in move_smb2_ea_to_cifs() [ Upstream Date: Tue, 06 Oct 2026 15:22:38 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98170 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: 3 X-AL-KERNEL-ActionableScore-Lower: 2 X-AL-KERNEL-Commit: d3546cecbf81d98bf3b472d341f981eb48c04f47 List-Id: CVE: CVE-2026-98170 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: smb: client: fix OOB struct field reads in move_smb2_ea_to_cifs() [ Upstream Commit: d3546cecbf81d98bf3b472d341f981eb48c04f47 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d3546cecbf81d98bf3b472d341f981eb48c04f47 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98170 Analysis date: Tue, 06 Oct 2026 15:22:38 -0400 ActionableScore: 3 ActionableScore lower bound: 2 Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98170 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98170 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-2026-98170 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98170 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H';CWE-125;*CWE-20;CWE-1285;Other CVSS 'AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L';BEST CVSS score: '7.1';DESCR 'An out of bounds structure field read can occur in the SMB client because move_smb2_ea_to_cifs may continue parsing when the remaining response buffer is smaller than a complete smb2_ea_info header. A malicious or compromised SMB server can return a truncated extended attribute entry or an invalid next_entry_offset in response to getxattr or listxattr and cause the client kernel to read beyond the supplied EA buffer. For the CVSS the PR:N value is used for the paranoid score because an attacker who controls the responding SMB server does not need an account or local code execution on the affected client. UI:R applies because the client must connect to the server and request extended attributes before the malformed response is processed. The direct primitive is an out of bounds read rather than a write or a demonstrated use after free. Impact is at least service degradation and may include a kernel fault or crash. Limited confidentiality impact is retained in the paranoid score because adjacent kernel memory can be read internally, although a reliable path for returning that data to the attacker is not established. SMB services are commonly used on internal enterprise networks, so practical exploitation generally requires the victim to access an attacker controlled or compromised file server.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) MAYBE OOB DANGER DISK SERVERTOCLIENT LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 2 * Conservative score: 2 * Raw paranoid score: 3 * Paranoid score: 3 * No floor or cap was applied. * Final recommended bucket: **Borderline / manual review recommended**:: 2. Signal breakdown Conservative signals: * +2 Remote reachable. An attacker-controlled or compromised SMB server can supply the malformed EA response after the client requests extended attributes. * +1 Broadly deployed exposure. SMB clients are common, and `getxattr` or `listxattr` can realistically exercise this parser on mounted shares. * -1 Highly constrained read-only access. The established primitive is a small OOB read of structure fields. No write, stale object, controlled target, or disclosure path is shown. * Total: 2. Paranoid addition: * +1 Plausible kernel fault. Reading a truncated header beyond the response allocation can trigger a memory-safety detector or fault if the access crosses inaccessible storage. * Total: 3. Not awarded: * No confidentiality point because bytes read outside the structure are not shown to be returned to userspace or the network. * No integrity point because no OOB write or subsequent write based on the invalid fields is established. * No UAF, controlled reclaim, arbitrary write, type confusion, callback influence, or privilege-escalation primitive is established. * No extra Availability point was awarded for the same possible kernel fault. * No practical exploit-chain point was awarded because the established chain ends at invalid parsing or a possible crash. 3. Reachability analysis The relevant attacker is a malicious or compromised SMB server, or an actor able to alter server responses. The client must already connect to the server and issue `getxattr` or `listxattr`, so victim interaction and an existing SMB mount are prerequisites. The remote attacker does not need host-administrator privileges or a local account on the client. Therefore `HostAdminRequired=NO`. The mount may have been created by a separate privileged actor, but that is victim-side deployment setup rather than attacker privilege. No namespace capability is part of the supplied path, so complete namespace-scoped reachability is unresolved and `NamespaceScopedPrivilege=UNKNOWN`. There is no race, special hardware dependency, boot option, or timing requirement. 4. Primitive and severity interpretation The exact primitive is an OOB read of `smb2_ea_info` fields when fewer than `sizeof(*src)` bytes remain. Invalid `next_entry_offset` values can also advance parsing so that a truncated entry is interpreted as a complete header. This is not a UAF, lifetime violation, repeated release, or active structured stale-object use. It is a read-only bounds-validation failure driven by network-originated data. `PrimitiveClass=CLASS_C` because the demonstrated behavior is invalid parsing with a possible crash, without an independently useful corruption or disclosure primitive. A kernel fault is technically plausible, but controlled disclosure, memory modification, and privilege escalation are not supported. `ImportantCandidate=NO` because the evidence does not establish an Important-preserving primitive. `AutoDowngradeAllowed=YES` because no unresolved write, lifetime, ownership, or authorization primitive would be lost by treating this as an ordinary or borderline Moderate issue. Likely operational severity is Low to Moderate, with higher attention justified when clients connect to untrusted SMB servers. 5. One-sentence report phrase A malicious SMB server can return a truncated extended attribute list that causes the Linux SMB client to read structure fields beyond the response buffer, potentially producing a kernel fault but with no demonstrated disclosure or write primitive. 6. Manual review recommendation MANUAL CHECK RECOMMENDED The input is remotely supplied and the OOB read is concrete, but review should focus on whether surrounding allocation and copy behavior creates an actual disclosure or reliable crash path rather than assuming stronger corruption. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: smb: client: fix OOB struct field reads in move_smb2_ea_to_cifs() [ Upstream Commit: d3546cecbf81d98bf3b472d341f981eb48c04f47 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d3546cecbf81d98bf3b472d341f981eb48c04f47 Changed files: fs/smb/client/smb2ops.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=d3546cecbf81d98bf3b472d341f981eb48c04f47 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98170 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98170 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:L The Best / paranoid CVSS vector: AV:N/AC:L/PR:N/UI:R/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: 2 Paranoid ActionableScore: 3 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).