From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72106][MODERATE 7.0] dm-ioctl: fix a possible overflow in list_version_get_info Date: Sat, 15 Aug 2026 04:39:28 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72106 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: 29536a9ff146d9bbd618959857ed2e691cda1d21 List-Id: CVE: CVE-2026-72106 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: dm-ioctl: fix a possible overflow in list_version_get_info Commit: 29536a9ff146d9bbd618959857ed2e691cda1d21 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=29536a9ff146d9bbd618959857ed2e691cda1d21 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72106 Analysis date: Sat, 15 Aug 2026 04:39:28 -0400 ActionableScore: 5 ActionableScore lower bound: 3 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: A bounds check bug in dm-ioctl list_version_get_info can allow a local caller with access to the device-mapper control ioctl to trigger a small kernel buffer overflow when listing target versions, with realistic DoS impact and limited but nonzero concern for privilege escalation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72106 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72106 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-2026-72106 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:H/I:H/A:H';*CWE-787;CWE-131;CWE-122;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'A kernel buffer overflow exists in the device mapper ioctl path because list_version_get_info checks space using sizeof(tt version), which covers only 12 bytes, while the code can write the full dm_target_versions header of 16 bytes plus the target name. A local caller that can issue the affected device mapper ioctl may be able to craft an output buffer size that passes the check but causes a small out of bounds write in kernel memory. For the CVSS the PR:L in the paranoid score is used because reduced capability administrators, container root with delegated device mapper access, or service accounts with CAP_SYS_ADMIN over /dev/mapper/control may reach this interface without being full host administrators. The issue is not network reachable and requires local access to the device mapper control interface. Impact is at least local denial of service via kernel memory corruption, and in the worst case may allow confidentiality or integrity impact and privilege escalation, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4) YES OOB DISK SIMPLEFIX LINUS INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN6 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: 3 * Paranoid score: 5 * Final recommended bucket: **Actionable Moderate at minimum** ## 2. Signal breakdown Paranoid scoring: * Constrained kernel buffer overwrite: +1 The bounds check used sizeof(tt->version), 12 bytes, while the later write can emit struct dm_target_versions, 16 bytes, plus the target name. * Weak LPE concern: +1 This is a real kernel OOB write, but the overwrite appears small and mostly kernel-derived, with no demonstrated attacker-controlled target or payload. * Privileged kernel/device-management memory corruption path: +1 The bug is in the device-mapper ioctl path, a trusted storage management subsystem. * Important filesystem/storage path: +1 Device mapper is an important block/storage management component. * Availability impact realistic: +1 A kernel heap overwrite in this path can plausibly cause a crash or corrupted kernel state. * Requires admin/root/CAP_SYS_ADMIN in typical deployments: -1 in paranoid scoring Typical access to /dev/mapper/control requires CAP_SYS_ADMIN, but reduced-capability root, container root with delegated device-mapper access, or service accounts may make PR:L a defensible triage assumption. Conservative scoring applies the full privilege penalty: * Same positive signals except weak LPE is treated cautiously. * Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2. * Conservative result: 3. Call-site confidence: medium. The patch shows the faulty size check and the commit message explicitly describes the 12 byte vs 16 byte write mismatch, but the full ioctl allocation and copyout call path is not included in the provided diff. ## 3. Reachability analysis The bug is locally reachable through the device-mapper ioctl interface, typically /dev/mapper/control. In normal deployments this requires CAP_SYS_ADMIN or equivalent administrative device-management privileges, so it is not a plain unprivileged local bug. Namespaces or containers may matter if device-mapper access is delegated to container root or a reduced-privilege service account, in which case the practical privilege level can be closer to PR:L than PR:H. The issue is not network reachable. ## 4. Severity interpretation This is stronger than an ordinary Moderate correctness bug because the patch fixes a concrete kernel buffer overflow. It is not enough to claim a strong LPE primitive from the diff alone because the overflow appears small, the written values are not clearly attacker-controlled, and no reclaim, object replacement, arbitrary write, or type confusion primitive is shown. Realistically it is at least a local privileged kernel memory corruption and DoS concern. Paranoid triage should keep it as Actionable Moderate because kernel OOB writes in storage management paths can be underestimated. ## 5. One-sentence report phrase A bounds check bug in dm-ioctl list_version_get_info can allow a local caller with access to the device-mapper control ioctl to trigger a small kernel buffer overflow when listing target versions, with realistic DoS impact and limited but nonzero concern for privilege escalation. ## 6. Manual review recommendation MANUAL CHECK REQUIRED. Reason: this is a concrete kernel OOB write in a storage management ioctl path, and although the primitive appears constrained, it should not be auto-closed without checking allocator context, object adjacency, and whether delegated device-mapper access exists in the target environment. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: dm-ioctl: fix a possible overflow in list_version_get_info Commit: 29536a9ff146d9bbd618959857ed2e691cda1d21 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=29536a9ff146d9bbd618959857ed2e691cda1d21 Commit description: sizeof(tt->version) is 12 bytes, but the code writes 16 bytes into the output buffer - info->vers->version[0], info->vers->version[1], info->vers->version[2] and info->vers->next. This can cause buffer overflow. Fix this buffer overflow by replacing "sizeof(tt->version)" with "sizeof(struct dm_target_versions)". Signed-off-by: Mikulas Patocka Assisted-by: Claude:claude-opus-4.6 Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Changed files: drivers/md/dm-ioctl.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=29536a9ff146d9bbd618959857ed2e691cda1d21 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72106 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72106 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:H/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 7.8 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).