From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-93146][LOW] time/namespace: Validate nanosecond field in proc_timens_set_offset() [ Upstream Date: Fri, 18 Sep 2026 03:35:57 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-93146 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: 2 X-AL-KERNEL-ActionableScore-Lower: 1 X-AL-KERNEL-Commit: db667d2970c756cc7b483f45f272440f845a665b List-Id: CVE: CVE-2026-93146 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: time/namespace: Validate nanosecond field in proc_timens_set_offset() [ Upstream Commit: db667d2970c756cc7b483f45f272440f845a665b Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=db667d2970c756cc7b483f45f272440f845a665b Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93146 Analysis date: Fri, 18 Sep 2026 03:35:57 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate Manual review required: NO Summary: `proc_timens_set_offset() failed to validate tv_nsec before timespec64_add(), allowing malformed time namespace offsets that may cause incorrect namespace time calculations but no demonstrated memory corruption, privilege escalation, or remote attack path.` ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93146 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93146 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-2026-93146 LOW https://www.kernelcve.org/list/?q=CVE-2026-93146 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L';*CWE-20;CWE-682;CWE-1284;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N';BEST CVSS score: '4.4';DESCR 'proc_timens_set_offset validated tv_sec but did not validate tv_nsec before using the value in timespec64_add. An invalid nanosecond field can be negative or greater than NSEC_PER_SEC and may cause incorrect time offset calculations or unexpected time namespace behavior. For the CVSS the PR:L is used because a local process with permission to write proc timens_offsets or namespace scoped CAP_SYS_TIME is needed. The issue is not network reachable and does not provide a known memory corruption primitive. Impact is mainly limited integrity impact inside the affected time namespace, with possible limited availability impact for applications that depend on correct namespace time values.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) YES SIMPLEFIX LINUS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES ## 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 2 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap changed the score. ## 2. Signal breakdown Conservative signals: * +1: Concrete input validation and logic bug. `proc_timens_set_offset()` accepted an invalid `tv_nsec` value before calling `timespec64_add()`, which expects normalized `timespec64` input. Paranoid signals: * +1: Same concrete input validation and logic bug. * +1: Limited practical availability or correctness impact is possible for applications inside the affected time namespace if invalid offsets cause unexpected time calculations. Non-awarded signals: * +0: No UAF, stale pointer, OOB access, double release, refcount corruption, or memory corruption primitive is established. * +0: No reliable kernel crash or host-wide DoS is demonstrated. * +0: No confidentiality impact is established. * +0: No meaningful integrity impact against host or another security principal is established. The effect appears limited to incorrect time namespace state. * +0: No authorization bypass is shown. * +0: No remote reachability is established. * +0: No resource leak or resource exhaustion is established. * +0: No privilege escalation path is supported by the patch or supplied context. ## 3. Reachability analysis The vulnerable operation is writing time namespace offsets via the proc interface handled by `proc_timens_set_offset()`. The complete privilege boundary is not fully visible in the supplied diff. Normal time namespace behavior suggests that a writer needs permission such as namespace-scoped `CAP_SYS_TIME` over the relevant time namespace, but the supplied patch does not fully establish whether an ordinary unprivileged user can create all required namespaces and perform the complete operation in the evaluated environment. Host-admin-equivalent privilege is therefore not positively established, but below-host-admin reachability is also not fully proven from the supplied evidence. No network trigger exists. No special hardware, firmware, race, or timing requirement is involved. No prior privileged device or subsystem setup is indicated beyond normal time namespace/procfs availability. ## 4. Primitive and severity interpretation The exact primitive is acceptance of a malformed nanosecond field in a time offset structure. This is an input validation / arithmetic correctness issue, not an active kernel memory corruption issue. The invalid value is consumed by `timespec64_add()`, which expects normalized inputs, and may produce incorrect or unexpected time namespace calculations. PrimitiveClass is `NONE` because there is no established corruption, ownership, authorization, lifetime, or security-boundary primitive. RealUAF is `NO`. The demonstrated consequence is incorrect time namespace behavior. The paranoid consequence is limited disruption to applications that depend on correct namespace time values. There is no patch-supported path to LPE, arbitrary read/write, information disclosure, or host-wide crash. ImportantCandidate is `NO` because no Important-grade primitive is established. AutoDowngradeAllowed is `YES` because this is a validation-only logic flaw with low practical security impact. ## 5. One-sentence report phrase `proc_timens_set_offset() failed to validate tv_nsec before timespec64_add(), allowing malformed time namespace offsets that may cause incorrect namespace time calculations but no demonstrated memory corruption, privilege escalation, or remote attack path.` ## 6. Manual review recommendation NO MANUAL CHECK NEEDED Reason: validation-only local logic issue, no memory corruption, no security-boundary bypass, no crash primitive, and no demonstrated privilege escalation path. ## 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: time/namespace: Validate nanosecond field in proc_timens_set_offset() [ Upstream Commit: db667d2970c756cc7b483f45f272440f845a665b Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=db667d2970c756cc7b483f45f272440f845a665b Changed files: kernel/time/namespace.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=db667d2970c756cc7b483f45f272440f845a665b ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93146 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93146 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:N/I:L/A:N The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L The Best / paranoid CVSS score: 4.4 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: 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).