From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99232][MODERATE 7.0] tracing/syscalls: Use copy_from_user for the faultable syscall buffer Date: Mon, 02 Nov 2026 23:01:18 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99232 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 5 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: e33e2718c62a602001ab549642a1aed0be797105 List-Id: CVE: CVE-2026-99232 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: tracing/syscalls: Use copy_from_user for the faultable syscall buffer Commit: e33e2718c62a602001ab549642a1aed0be797105 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e33e2718c62a602001ab549642a1aed0be797105 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99232 Analysis date: Mon, 02 Nov 2026 23:01:18 -0400 ActionableScore: 5 ActionableScore lower bound: 3 Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review Manual review required: YES Summary: Missing `access_ok()` permits attacker-selected kernel addresses to be copied into syscall trace records, with exploitability depending on unresolved tracing/perf record access. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99232 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99232 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 7.0 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-2026-99232 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-99232 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=MODERATE RESULT=DIFF (final Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC) 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-200;*CWE-20;CWE-125;BEST CVSS score: '5.5';DESCR 'The syscall tracing path used __copy_from_user for faultable syscall buffers and therefore skipped access_ok validation of an attacker controlled pointer. A local process can place a kernel address in a write or pwrite64 buffer argument even when the syscall itself later rejects that address. If the relevant syscall event is enabled and its records are available through tracing or perf, kernel bytes may be copied into the event record and disclosed. For the CVSS the PR:L value reflects that exploitation requires a local user context and practical access to the generated tracing or perf records. Confidentiality impact is high because repeated calls can provide a kernel memory read primitive, while the patch provides no evidence of memory writes, integrity impact, or a kernel crash. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 5.5 and the production ActionableScore returned 4 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage LOW to MODERATE_KPANIC because the manual review requirement was applied. KP and FD specialist checks stage MODERATE_KPANIC to MODERATE because KP specialist did not establish a qualifying panic. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK and DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP and V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 2 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 4) MAYBE OOB TRACE SIMPLEFIX LEAK LINUS INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=3 PrimitiveClass=CLASS_B RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=YES ManualReview=REQUIRED AutoDowngradeAllowed=NO RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=UNRESOLVED B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 3. * Conservative score: 3; no floor or cap applied. * Raw paranoid score: 5. * Paranoid score: 5; no floor or cap applied. * Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**:: 2. Signal breakdown * +2: Concrete attacker-selected kernel-address read candidate. `__copy_from_user()` omits `access_ok()`, allowing a syscall buffer pointer outside userspace to be copied into a trace-event record. * +1: Local unprivileged invocation of the faultable syscall is grounded; the syscall can reject the address after tracing has already attempted the copy. * Paranoid +1: Confidentiality is plausible if the attacker can read the generated tracing/perf record. * Paranoid +1: A practical repeated-read chain is technically credible from attacker-selected pointers to event records, but record access and event enablement are not established by the patch. * No write, UAF, OOB write, crash, integrity impact, LPE, or arbitrary kernel access is shown. * No B4 authorization bypass: `access_ok()` is an address-range validation, not the required credential/capability/security-state authorization decision. * NEW52/B5-R and NEW53/B3-PENDING do not apply. 3. Reachability analysis An ordinary process can submit a kernel-range pointer to `write`, `pwrite64`, or another traced faultable syscall. The complete disclosure path additionally requires the relevant syscall event to be enabled and the resulting tracing/perf record to be readable by that actor. The supplied patch does not establish who enables the event, applicable `perf_event_paranoid` or tracefs permissions, delegation, or whether prior privileged setup is required. Therefore effective host-admin and namespace requirements remain unknown. 4. Primitive and severity reading The primitive is an attacker-directed kernel-memory copy into a kernel trace record caused by omitted user-address validation. It is CLASS_B because the copy is real, but delivery of those bytes to a below-host-admin reader is unresolved. If record access is available, repeated calls could form a meaningful kernel disclosure primitive; the patch alone does not prove that complete chain. ImportantCandidate is retained because this downstream trust boundary materially determines whether the issue is an internal trace-buffer modification or an exploitable disclosure. 5. One-sentence report phrase Missing `access_ok()` permits attacker-selected kernel addresses to be copied into syscall trace records, with exploitability depending on unresolved tracing/perf record access. 6. Manual review advice MANUAL CHECK REQUIRED Verify event-enablement and record-read permissions for unprivileged or delegated perf/trace users. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: tracing/syscalls: Use copy_from_user for the faultable syscall buffer Commit: e33e2718c62a602001ab549642a1aed0be797105 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e33e2718c62a602001ab549642a1aed0be797105 Commit description: syscall_copy_user_array() copies the buffer argument of faultable syscalls (write, pwrite64, ...) with __copy_from_user(), which skips access_ok(). Use copy_from_user() instead so a non-user address is rejected and the entry is recorded as faulted. It could be a security concern for machines that trust perf a bit too much. Cc: stable@vger.kernel.org Fixes: baa031b ("tracing: Allow syscall trace events to read more than one user parameter") Link: https://patch.msgid.link/6ad19afd.a938ce27.16851e.3440@mx.google.com Signed-off-by: Haoran Wang Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman Changed files: kernel/trace/trace_syscalls.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=e33e2718c62a602001ab549642a1aed0be797105 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99232 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99232 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: Not available 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: 3 Paranoid ActionableScore: 5 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 7.0 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).