From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-93801][LOW] smb/client: zero-initialize stack-allocated cifs_open_info_data [ Upstream Date: Thu, 24 Sep 2026 14:35:07 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-93801 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: 0 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 74ff47e6c4213fcfeba2de448d9cbda200507d22 List-Id: CVE: CVE-2026-93801 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: smb/client: zero-initialize stack-allocated cifs_open_info_data [ Upstream Commit: 74ff47e6c4213fcfeba2de448d9cbda200507d22 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=74ff47e6c4213fcfeba2de448d9cbda200507d22 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93801 Analysis date: Thu, 24 Sep 2026 14:35:07 -0400 ActionableScore: 0 ActionableScore lower bound: unknown 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-2026-93801 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93801 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-2026-93801 LOW https://www.kernelcve.org/list/?q=CVE-2026-93801 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:L';*CWE-457;CWE-665;CWE-908;*CWE-457;Other CVSS 'AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:N';BEST CVSS score: '4.2';DESCR 'An uninitialized stack allocated cifs_open_info_data structure can contain residual values when some fields are not populated by later SMB client operations. This can cause incorrect client side handling of open information in SMB1 SMB2 or symlink related paths. The shown changes do not establish a use after free out of bounds access uninitialized memory disclosure or write primitive. For the CVSS the PR:N value is used for the paranoid score because a malicious remote SMB server could potentially influence reply processing after a victim client connects to that server. A victim still needs to mount or access the attacker controlled SMB service. The realistic impact is an incorrect client operation or limited denial of service. Privilege escalation is not supported by the available code context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) YES DISK SERVERTOCLIENT DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 0 * Conservative score: 0 * Raw paranoid score: 0 * Paranoid score: 0 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap was applied. 2. Signal breakdown * 0: The patch establishes uninitialized stack allocation of `struct cifs_open_info_data` in three SMB client paths. This is a correctness and initialization defect, but no concrete memory-corruption primitive is shown. * 0: No UAF, stale object, refcount misuse, double release, OOB access, or lifetime violation is established. * 0: No attacker-controlled write, controlled reclaim, type confusion, callback dispatch, or active-object replacement is established. * 0: No confidentiality impact is awarded. The supplied context does not show uninitialized stack bytes copied to userspace, transmitted over SMB, logged, or otherwise exposed. * 0: No integrity impact is awarded. Incorrect residual field values may affect client behavior, but no unauthorized modification of protected state is established. * 0: No availability point is awarded. The commit does not document a crash, hang, filesystem shutdown, or reproducible DoS. * 0: Remote reachability is not awarded. A malicious SMB server could potentially participate only after a victim has mounted or accessed that server, but the supplied code does not establish a remotely controllable trigger or harmful consequence. * 0: No privilege-escalation or security-boundary signal is established. * 0: No negative privilege or niche-subsystem penalty is applied because the relevant attacker privilege and deployment requirements are unresolved rather than positively restrictive. 3. Reachability analysis The affected code is in the SMB client and executes after a system has configured and used an SMB mount or SMB client connection. The supplied patch does not show whether a remote SMB server can deliberately cause individual `cifs_open_info_data` fields to remain unset and later affect a security-relevant operation. A remote attacker would at minimum need the victim to connect to an attacker-controlled SMB server or resource. That prerequisite alone does not establish direct remote exploitation, a crash primitive, or a below-host-admin complete trigger chain. Host-admin-equivalent privilege is not positively established as required for the vulnerable operation, but below-host-admin reachability is also not positively established. Therefore `HostAdminRequired=UNKNOWN`. No namespace-specific capability path is shown. Therefore `NamespaceScopedPrivilege=UNKNOWN`. No special hardware, boot parameter, sysctl, race condition, repeated lifetime transition, or prior privileged setup is established by the supplied diff. 4. Primitive and severity interpretation The exact primitive is use of a stack-allocated `cifs_open_info_data` object whose fields may retain residual stack values when later code does not initialize them. This is an initialization and invalid-state issue, not a demonstrated lifetime or memory-corruption issue. The patch only changes three declarations to `= {}`. The supplied context does not include the structure definition, consuming call paths, or evidence that any uninitialized member is serialized, dereferenced as a pointer, used as a length or offset, or used to bypass authorization. This is neither active structured stale-object use nor fixed stale storage. There is no release, put, free, refcount mutation, or repeated lifetime operation. There is no demonstrated crash, disclosure, integrity violation, privilege escalation, or security-boundary bypass. `PrimitiveClass=NONE` is appropriate because no meaningful corruption, lifetime, ownership, authorization, or similar security primitive is established. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` are appropriate because there is no unresolved concrete kernel-corruption primitive that would be lost through automated downgrade. Likely operational severity is a low-risk correctness issue. It may justify normal maintenance patching, but the supplied evidence does not support Important-class security triage. 5. One-sentence report phrase Uninitialized stack allocated cifs_open_info_data instances could retain incorrect field values in SMB client operations, but the supplied patch does not establish a memory-corruption, disclosure, privilege-escalation, or reliable denial-of-service primitive. 6. Manual review recommendation NO MANUAL CHECK NEEDED The available patch establishes only defensive zero initialization and does not provide evidence of a concrete exploitable primitive or security-relevant consequence. 7. Call-site confidence Call-site confidence: low ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: smb/client: zero-initialize stack-allocated cifs_open_info_data [ Upstream Commit: 74ff47e6c4213fcfeba2de448d9cbda200507d22 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=74ff47e6c4213fcfeba2de448d9cbda200507d22 Changed files: fs/smb/client/link.c fs/smb/client/smb1ops.c 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=74ff47e6c4213fcfeba2de448d9cbda200507d22 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93801 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93801 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:H/PR:N/UI:R/S:U/C:N/I:N/A:N The Best / paranoid CVSS vector: AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:L The Best / paranoid CVSS score: 4.2 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: unknown Paranoid ActionableScore: 0 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).