From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72096][LOW] dm-verity: make error counter atomic [ Upstream Date: Sat, 15 Aug 2026 13:17:59 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72096 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: ac99781115d37d10894653b47941d9d8fc26fa64 List-Id: CVE: CVE-2026-72096 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: dm-verity: make error counter atomic [ Upstream Commit: ac99781115d37d10894653b47941d9d8fc26fa64 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ac99781115d37d10894653b47941d9d8fc26fa64 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72096 Analysis date: Sat, 15 Aug 2026 13:17:59 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A race in dm-verity corrupted block error accounting can lose updates to the corrupted_errs counter and skip the max-corrupted-errors audit event, but it does not provide a memory corruption primitive and is mainly a low-impact audit integrity issue. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72096 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72096 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-2026-72096 LOW CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L';CWE-362;CWE-667;CWE-778;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N';BEST CVSS score: '3.6';DESCR 'dm-verity used a non-atomic corrupted_errs counter while handling verification errors for corrupted blocks. Concurrent error handling can lose counter updates and may skip the max-corrupted-errors audit event even though the corrupted block handling path still marks the verity device as failed. For the CVSS the PR:L is used because a local process can help trigger reads from an affected dm-verity device, but reliable exploitation also depends on already corrupted blocks or control of the lower storage layer. The issue is not network reachable and does not provide a memory corruption primitive. Impact is mainly low integrity impact to audit reliability and at most limited availability impact if repeated corrupted block handling causes operational degradation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) YES DANGER DISK SIMPLEFIX RACE ERRORPATH HARDWARE LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown Triggered signals: * Local unprivileged trigger: +1 A local process may help trigger the error path by reading from an affected dm-verity device, but only if corrupted blocks already exist or the lower storage layer is attacker-influenced. * Important filesystem/storage path: +1 dm-verity is a storage integrity subsystem, so accounting and audit behavior is security-relevant. * Integrity impact plausible: +1 The impact is limited to audit and monitoring integrity. The `max-corrupted-errors` audit event may be skipped due to lost counter updates. Negative signals: * Hard or unreliable race / special timing required: -1 The issue requires concurrent handling of corrupted block errors and a race on the counter. * Corruption primitive highly constrained or metadata-only: -1 This is an accounting/audit race only. No UAF, OOB access, arbitrary write, stale pointer, or memory lifetime corruption is shown. Conservative score is 1 if local triggering is treated as dependent on pre-existing corrupted storage. Paranoid score is 2 if ordinary local reads from an already affected dm-verity volume are considered sufficient for practical triggering. ## 3. Reachability analysis The bug is local, not network reachable. A local process can potentially cause reads from a dm-verity protected device, but reliable triggering requires corrupted blocks and concurrent error handling. Creating those corrupted blocks usually requires control of the lower storage layer, device image, or administrative access. Namespaces and containers do not obviously lower the privilege requirement for creating corrupted backing storage. They may allow reading exposed dm-verity-backed files, but that alone does not create the corruption condition. The affected subsystem is commonly used in integrity-protected systems, but this specific bug affects error accounting and audit logging rather than verification correctness. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like issue, not an Important-class vulnerability. There is no demonstrated memory corruption primitive. The patch converts `corrupted_errs` from a non-atomic integer to `atomic_t` and uses compare-exchange to avoid lost updates. The corrupted block path still marks `hash_failed`, and the data verification failure is still handled. The main security consequence is that the maximum corrupted errors audit event may be missed. Theoretical impact is limited audit integrity degradation. Realistic exploitation as privilege escalation, information disclosure, or kernel memory corruption is not supported by the patch. ## 5. One-sentence report phrase A race in dm-verity corrupted block error accounting can lose updates to the corrupted_errs counter and skip the max-corrupted-errors audit event, but it does not provide a memory corruption primitive and is mainly a low-impact audit integrity issue. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can be auto-closed for urgent triage purposes unless dm-verity audit completeness is a strict compliance requirement for the evaluated product. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: dm-verity: make error counter atomic [ Upstream Commit: ac99781115d37d10894653b47941d9d8fc26fa64 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ac99781115d37d10894653b47941d9d8fc26fa64 Changed files: drivers/md/dm-verity-target.c drivers/md/dm-verity.h 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=ac99781115d37d10894653b47941d9d8fc26fa64 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72096 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72096 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:H/PR:L/UI:N/S:U/C:N/I:L/A:N The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L The Best / paranoid CVSS score: 3.6 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).