From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72365][MODERATE REGULAR] netfs: Fix writethrough to use collection offload [ Upstream Date: Sun, 16 Aug 2026 05:58:21 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72365 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: 4 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: 7838131e296dfbb639ea278901a53c018322c11e List-Id: CVE: CVE-2026-72365 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: netfs: Fix writethrough to use collection offload [ Upstream Commit: 7838131e296dfbb639ea278901a53c018322c11e Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7838131e296dfbb639ea278901a53c018322c11e Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72365 Analysis date: Sun, 16 Aug 2026 05:58:21 -0400 ActionableScore: 4 ActionableScore lower bound: 3 Actionable bucket: Borderline Moderate / Manual review recommended but not Important candidate Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72365 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72365 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-2026-72365 MODERATE 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:H';*CWE-664;CWE-703;*CWE-772;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '6.1';DESCR 'netfs writethrough O_SYNC writes can miss asynchronous request collection because NETFS_RREQ_OFFLOAD_COLLECTION is not set on the request. This can leave completion and error handling delayed or absent for affected writes, with possible data sync semantic breakage, resource retention, or stalled write completion depending on the filesystem and workload. For the CVSS the PR:L is used because a local user or process with write access to a netfs mount can trigger the affected write path, while administrator privileges are not normally required once the mount exists. The issue is not directly network reachable from packet traffic and does not show a UAF, OOB access, arbitrary write, or info leak primitive. Impact is mainly local integrity and availability degradation, not privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Borderline Moderate / Manual review recommended but not Important candidate (with actual score 4) SKIP CVE-2026-72365 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 288ace2f57c9d06dd2e42bd80d03747d879a4068 YES NO NO unknown MAYBE REMOTE DISK SIMPLEFIX LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=3 1. **ActionableScore** * Conservative score: 3 * Paranoid score: 4 * Final recommended bucket: **Borderline Moderate / Manual review recommended but not Important candidate** 2. **Signal breakdown** * Local unprivileged trigger: +1. A local process with write access to an already mounted netfs-backed filesystem can reach the writethrough O_SYNC write path. * Important filesystem/storage path: +1. The bug is in netfs writeback/writethrough request handling, which affects filesystem I/O completion semantics. * Integrity impact plausible: +1. Missing collection can affect O_SYNC write completion and sync semantics, so data consistency expectations may be weakened. * Availability impact realistic, paranoid only: +1. If asynchronous O_SYNC writes are not collected, affected workloads may see stalled completions or resource retention, but there is no demonstrated kernel crash or memory corruption. * No memory corruption signal. The patch only sets NETFS_RREQ_OFFLOAD_COLLECTION and does not show UAF, OOB access, arbitrary write, double free, refcount misuse, or stale pointer use. * No remote/network-triggerable signal. This is not reachable by packets alone. * No privilege escalation signal. No credible LPE primitive is shown. * Call-site confidence: medium. The changed function is visible, but deeper request collection call paths are not included in the patch snippet. 3. **Reachability analysis** A local user or process can plausibly trigger the affected path by issuing writethrough or O_SYNC writes to a mounted netfs filesystem. Administrator privileges are normally required to create the mount, but not necessarily to write to it once mounted and permissions allow access. Containers may reduce the practical privilege requirement if the netfs mount is exposed inside the container. The path is not directly network reachable, although the backing filesystem may be network based. Realistic exploitation appears workload dependent and limited to I/O semantic breakage, stalled completion, or resource retention. 4. **Severity interpretation** This behaves more like a borderline Moderate filesystem I/O correctness issue than an Important kernel vulnerability. The theoretical impact includes local integrity degradation and availability problems for affected O_SYNC write workloads. The realistic evidence does not support memory corruption, privilege escalation, information disclosure, or a reliable host crash. The paranoid score is raised only for possible high availability impact from uncollected asynchronous writes. 5. **One-sentence report phrase** A netfs writethrough request may miss asynchronous collection for O_SYNC writes, causing possible sync semantic breakage, delayed completion, or resource retention for local users with write access to an affected netfs mount. 6. **Manual review recommendation** MANUAL CHECK RECOMMENDED Reason: score is borderline due to filesystem writeback semantics and possible O_SYNC correctness impact, but there is no memory corruption, no remote trigger, and no LPE evidence, so this should not be treated as an Important candidate without additional evidence. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: netfs: Fix writethrough to use collection offload [ Upstream Commit: 7838131e296dfbb639ea278901a53c018322c11e Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7838131e296dfbb639ea278901a53c018322c11e Changed files: fs/netfs/write_issue.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=7838131e296dfbb639ea278901a53c018322c11e ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72365 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72365 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:L The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H The Best / paranoid CVSS score: 6.1 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: 3 Paranoid ActionableScore: 4 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).