From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-68293][MODERATE 7.0] net/mlx5: Fix MCIA register buffer overflow on 32 dword reads [ Upstream Date: Mon, 10 Aug 2026 13:10:42 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-68293 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 6 X-AL-KERNEL-ActionableScore-Lower: 4 X-AL-KERNEL-Commit: 5be4eebd5a3a198dab0adcd550e1cadca79bdfed List-Id: CVE: CVE-2026-68293 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: net/mlx5: Fix MCIA register buffer overflow on 32 dword reads [ Upstream Commit: 5be4eebd5a3a198dab0adcd550e1cadca79bdfed Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5be4eebd5a3a198dab0adcd550e1cadca79bdfed Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68293 Analysis date: Mon, 10 Aug 2026 13:10:42 -0400 ActionableScore: 6 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: The mlx5 MCIA register layout allowed up to 32 dword firmware reads into a structure that only modeled 12 dwords, causing an OOB read during ethtool module EEPROM access that can crash the kernel with FORTIFY_SOURCE and may otherwise expose adjacent kernel memory. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68293 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68293 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-2026-68293 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:N/A:H';CWE-125;CWE-126;*CWE-787;CWE-120;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H';BEST CVSS score: '7.1';DESCR 'An out of bounds read in the mlx5 MCIA register handling can occur when the device advertises mcia_32dwords and the driver reads up to 32 dwords from a register layout that only reserved space for 12 dwords. Reading module EEPROM data through ethtool can make mlx5_query_mcia copy past the end of the local output buffer. On kernels with FORTIFY_SOURCE this is detected as a memcpy buffer overflow and can crash the kernel. Without fortify the same bug can expose adjacent kernel memory through the EEPROM read result, so the realistic impact is local denial of service with possible information disclosure. For the CVSS the PR:L is chosen because a local process with permission to query module EEPROM or delegated network administration capability is needed for reliable triggering. The issue is not directly network reachable through packet traffic and depends on affected mlx5 hardware or firmware capability.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5) SKIP CVE-2026-68293 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE REMOTE OOB DANGER NETWORK HARDWARE KPANIC - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=6 ActionableScoreLower=4 ## 1. ActionableScore * Conservative score: 4 * Paranoid score: 6 * Final recommended bucket: **Actionable Moderate at minimum** ## 2. Signal breakdown Conservative signals: * Firmware-mediated external influence: +1. The unsafe size depends on the device advertising `mcia_32dwords`. * Weak OOB read primitive: +1. The bug is a read past the declared MCIA output layout, not an OOB write. * Reliable kernel crash / strong DoS: +1. The commit shows a FORTIFY_SOURCE detected memcpy overflow leading to `kernel BUG`. * Confidentiality impact plausible: +1. Without fortify, bytes past the intended register output area may be copied into the module EEPROM response. * Privileged or delegated device-management path: -1. Triggering usually involves ethtool module EEPROM access, commonly restricted by permissions or CAP_NET_ADMIN-like delegation. * Hardware / capability dependency: -1. The issue depends on mlx5 hardware and the `mcia_32dwords` capability. Paranoid additions / interpretation: * Local trigger through device-management API: +1. If ethtool EEPROM reads are available to a non-root or delegated network-management context, the practical trigger is not full host-root. * Data-center common driver exposure: +1. mlx5 is common in server and storage/networking deployments, even though the bug is hardware-specific. ## 3. Reachability analysis The bug is triggered from the mlx5 module EEPROM read path, visible in the trace through ethtool netlink handling and `mlx5_query_mcia()`. It is not reachable through normal packet traffic and should not be treated as remote network-triggerable. The attacker generally needs local access to query module EEPROM data, or access through a delegated network-management context such as CAP_NET_ADMIN in a namespace or service account. The vulnerable behavior also depends on affected mlx5 hardware or firmware advertising 32 dword MCIA reads. Call-site confidence: high. The provided trace and patch show the relevant caller chain and the exact `memcpy()` source pointer correction. ## 4. Severity interpretation This is more than an ordinary cleanup because it is a concrete OOB read with a demonstrated kernel crash under FORTIFY_SOURCE. Realistic impact is local DoS, and plausible additional impact is kernel information disclosure if adjacent bytes are copied back through the EEPROM read result. There is no supported write primitive, reclaim primitive, UAF, callback control, or type confusion, so this should not be classified as a strong privilege-escalation candidate. It is best treated as Actionable Moderate, with manual review required because the OOB read may disclose kernel memory depending on layout and hardening. ## 5. One-sentence report phrase The mlx5 MCIA register layout allowed up to 32 dword firmware reads into a structure that only modeled 12 dwords, causing an OOB read during ethtool module EEPROM access that can crash the kernel with FORTIFY_SOURCE and may otherwise expose adjacent kernel memory. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: this is a concrete OOB read with a confirmed kernel crash and plausible information disclosure path, although no integrity impact or privilege-escalation primitive is demonstrated by the patch. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net/mlx5: Fix MCIA register buffer overflow on 32 dword reads [ Upstream Commit: 5be4eebd5a3a198dab0adcd550e1cadca79bdfed Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5be4eebd5a3a198dab0adcd550e1cadca79bdfed Changed files: lib/string_helpers.c drivers/net/ethernet/mellanox/mlx5/core/port.c include/linux/mlx5/mlx5_ifc.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=5be4eebd5a3a198dab0adcd550e1cadca79bdfed ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68293 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68293 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:L/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H The Best / paranoid CVSS score: 7.1 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: 4 Paranoid ActionableScore: 6 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: YES 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).