From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98169][MODERATE REGULAR] smb: client: fix potential OOB read in smb3_enum_snapshots() Date: Tue, 06 Oct 2026 15:09:42 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98169 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: 15a221c734b9d044ab769e7e3606b2cab96fb65a List-Id: CVE: CVE-2026-98169 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: smb: client: fix potential OOB read in smb3_enum_snapshots() Commit: 15a221c734b9d044ab769e7e3606b2cab96fb65a Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=15a221c734b9d044ab769e7e3606b2cab96fb65a Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98169 Analysis date: Tue, 06 Oct 2026 15:09:42 -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-2026-98169 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98169 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-2026-98169 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98169 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N';CWE-125;*CWE-200;CWE-130;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.5';DESCR 'An out of bounds read occurs in smb3_enum_snapshots when an SMB server returns a reply shorter than struct smb_snapshot_array and snapshot_array_size is below GMT_TOKEN_SIZE. The code can increase ret_data_len to 12 bytes even though SMB2_ioctl allocated retbuf using the smaller server supplied OutputCount. The following copy_to_user then reads beyond retbuf and discloses adjacent kernel slab memory to the local calling process. For the CVSS the PR:L value is selected because practical exploitation requires a local process with access to the mounted SMB share and the ability to request snapshot enumeration, even though the malformed length originates from a network server. The base impact is limited confidentiality loss from a small kernel memory disclosure. Repeated requests may expose more sensitive slab data, so the paranoid score uses C:H while keeping I:N and A:N because no write primitive or crash is demonstrated. This is not a pure remote information leak because the disclosed bytes are returned to local userspace rather than sent back to the SMB server.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) MAYBE OOB DISK SIMPLEFIX LEAK IMPROVEONLY SERVERTOCLIENT LINUS INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 PrimitiveClass=CLASS_B RealUAF=NO HostAdminRequired=UNKNOWN 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: * +1 Concrete limited OOB-read primitive. `ret_data_len` can exceed the server-sized `retbuf`, causing `copy_to_user()` to read up to the 12-byte structure size from a shorter allocation. * +1 Confidentiality plausible. Adjacent kernel slab bytes are explicitly copied to local userspace. * 0 Memory-layout invariant restoration. This is not scored separately because it describes the same allocation-size versus copy-size mismatch as the OOB read. * 0 Remote reachability. The server controls `OutputCount`, but leaked bytes are returned to the local caller rather than to the remote server. * 0 Availability and integrity. No write, corruption, crash, or persistent availability effect is established. Paranoid additional signal: * +1 Weak exploitation leverage. Repeated snapshot queries may sample adjacent slab contents and potentially disclose pointers or other sensitive kernel data, although stable or attacker-selected disclosure is not demonstrated. Important non-awarded signals: * No controlled target selection or arbitrary kernel read is established. * No kernel write, controlled reclaim, UAF, callback influence, or privilege escalation is established. * No local-unprivileged bonus is awarded because the complete ability to obtain the relevant SMB mount, influence the server, and invoke snapshot enumeration as one below-host-admin principal is unresolved. * The bounded disclosure is not treated as a substantial Class A kernel disclosure. 3. Reachability analysis The malformed length originates from an SMB server response. Practical exploitation additionally requires a local process to invoke snapshot enumeration on the mounted share, because `copy_to_user()` returns the leaked bytes to that process. The supplied evidence does not establish whether an ordinary user can complete the full sequence, whether an administrator must first mount or expose the share, or whether one attacker can both control the server response and invoke the local operation. Therefore `HostAdminRequired=UNKNOWN`, and no privilege penalty or local-unprivileged bonus is applied. No namespace-scoped capability path is shown. No special hardware, race, timing window, or boot option is involved. The malformed response produces a deterministic size mismatch once the vulnerable call path is reached. 4. Primitive and severity interpretation The exact primitive is a bounded kernel heap OOB read with a concrete disclosure sink through `copy_to_user()`. Depending on the server-supplied reply length, up to the difference between that length and 12 bytes can be read beyond `retbuf`. This is not a UAF, stale-object operation, repeated release, or overwrite. Active-versus-fixed stale-storage classification is therefore inapplicable. The demonstrated consequence is disclosure of adjacent slab memory to a local process. Repeated disclosure of useful kernel data is plausible but not proven to be stable or attacker-directed. `PrimitiveClass=CLASS_B` reflects a real, potentially useful disclosure primitive that needs leverage analysis but does not establish the substantial disclosure or arbitrary-read control expected for Class A. `ImportantCandidate=NO` because no strong exploitation chain or broad disclosure is demonstrated. `AutoDowngradeAllowed=YES` because the primitive is bounded and no unresolved write, lifetime, ownership, or authorization-boundary violation remains. Likely operational severity is Moderate to borderline Actionable Moderate, depending on local ioctl permissions and whether repeated calls expose useful slab contents. 5. One-sentence report phrase A short attacker-influenced SMB snapshot reply can cause `smb3_enum_snapshots()` to copy beyond its response buffer and disclose adjacent kernel slab memory to the local calling process. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Verify the local caller permissions, mount provisioning requirements, maximum bytes disclosed per request, allocator behavior across repeated requests, and whether useful kernel pointers or secrets can be recovered reliably. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: smb: client: fix potential OOB read in smb3_enum_snapshots() Commit: 15a221c734b9d044ab769e7e3606b2cab96fb65a Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=15a221c734b9d044ab769e7e3606b2cab96fb65a Commit description: If snapshot_array_size is smaller than GMT_TOKEN_SIZE, smb3_enum_snapshots() sets ret_data_len to sizeof(struct smb_snapshot_array) without verifying the actual length of the server's reply. Because SMB2_ioctl() places no lower bound on the server-supplied OutputCount and allocates retbuf to exactly that length, a short reply results in ret_data_len exceeding the size of retbuf. The subsequent copy_to_user() then reads past the end of retbuf, leaking adjacent slab memory to userspace. The subsequent clamp check is ineffective as it only reduces ret_data_len. Fix this by rejecting replies shorter than sizeof(struct smb_snapshot_array) with -EIO. Note that the bound is set to the 12-byte struct size rather than the 16-byte MIN_SNAPSHOT_ARRAY_SIZE defined in MS-SMB2 3.3.5.15.1, because 12 bytes is exactly what copy_to_user() attempts to read. Fixes: e02789a ("smb3: enumerating snapshots was leaving part of the data off end") Cc: stable@vger.kernel.org Signed-off-by: Frank Sorenson Reviewed-by: David Howells Signed-off-by: Paulo Alcantara Signed-off-by: Greg Kroah-Hartman 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=15a221c734b9d044ab769e7e3606b2cab96fb65a ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98169 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98169 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:L/UI:N/S:U/C:L/I:N/A:N The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N 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: 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).