From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-45994][MODERATE REGULAR] ibmasm: fix OOB reads in command_file_write due to missing size checks Date: Wed, 27 May 2026 17:41:57 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-45994 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: 2 X-AL-KERNEL-Commit: a672682d39dd34e2b5ba4feb436723bed65125ff List-Id: CVE: CVE-2026-45994 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: ibmasm: fix OOB reads in command_file_write due to missing size checks Commit: a672682d39dd34e2b5ba4feb436723bed65125ff Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a672682d39dd34e2b5ba4feb436723bed65125ff Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45994 Analysis date: Wed, 27 May 2026 17:41:57 -0400 ActionableScore: 4 ActionableScore lower bound: 2 Actionable bucket: Borderline, manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45994 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45994 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-2026-45994 MODERATE CHECK 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:L';CWE-125;CWE-126;*CWE-200;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '6.1';DESCR 'ibmasm command_file_write() can accept a short user buffer whose dot command header declares a larger command and data size. Later size and timeout parsing and memcpy_toio() can read beyond the allocated kernel buffer and copy adjacent kernel heap bytes to the service processor MMIO path. For the CVSS the PR:L is used in the paranoid score because access to the ibmasm command file may be delegated to a service or reduced privilege operator, although typical deployments may require administrator level device access. The issue is not network reachable by itself and does not provide a kernel write primitive. Impact is mainly confidentiality exposure of kernel heap data to the service processor side, with possible local DoS if invalid MMIO or malformed command handling fails.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 3) SKIP CVE-2026-45994 SKIP No affected files built, so skip this CVE NO - - unknown MAYBE WRITE OOB SIMPLEFIX LEAK LINUS INCREASED_TO_MODERATE7_FROM_MODERATE_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=2 1. ActionableScore * Conservative score: 2 * Paranoid score: 4 * Final recommended bucket: **Borderline, manual review recommended**:: 2. Signal breakdown * Weak memory disclosure primitive: +1. The bug causes OOB reads from a kernel heap buffer, but the read data is copied to the service processor MMIO path rather than directly returned to userspace. * Confidentiality impact plausible: +1. Adjacent kernel heap bytes may be exposed to the service processor side. * Availability impact plausible: +1. Malformed command handling or invalid device/MMIO interaction may cause local device-path failure or DoS. * Privileged kernel/device-management path: +1. The bug is in a trusted device command path interacting with IBM ASM service processor hardware. * Requires privileged or delegated device access: -1 to -2. Typical access to the ibmasm command file is expected to be administrator-only, but delegated service/operator access is plausible. * Rare hardware/configuration exposure: -1. This requires ibmasm hardware/driver presence. * No kernel write primitive. No UAF, arbitrary write, page-cache corruption, or LPE path is shown. 3. Reachability analysis The trigger is local through `command_file_write()` on the ibmasmfs command file. In typical deployments, access is likely restricted to root or a privileged service, but a reduced-privilege management agent could have delegated access. The issue is not network reachable by itself. Practical confidentiality impact depends on whether the attacker can observe or control the service processor side after kernel heap bytes are copied to MMIO. 4. Severity interpretation This is not ordinary crash-only Moderate because the patch explicitly describes kernel heap OOB reads and data copied to a device/service-processor channel. However, it is not a clear Important candidate because the leak is not directly returned to userspace and exploitation depends on specialized IBM ASM hardware and permissions. It fits borderline/manual-review territory. 5. One-sentence report phrase `ibmasm` command handling can trust user-controlled dot-command length fields, causing OOB kernel heap reads that may copy adjacent kernel data to the service processor MMIO path. 6. Manual review recommendation MANUAL CHECK RECOMMENDED. The bug has a real kernel heap OOB-read component, but practical severity depends on ibmasm command-file permissions and whether the service processor side is observable by the attacker. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ibmasm: fix OOB reads in command_file_write due to missing size checks Commit: a672682d39dd34e2b5ba4feb436723bed65125ff Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a672682d39dd34e2b5ba4feb436723bed65125ff Commit description: The command_file_write() handler allocates a kernel buffer of exactly count bytes and copies user data into it, but does not validate the buffer against the dot command protocol before passing it to get_dot_command_size() and get_dot_command_timeout(). Since both the allocation size (count) and the header fields (command_size, data_size) are independently user-controlled, an attacker can cause get_dot_command_size() to return a value exceeding the allocation, triggering OOB reads in get_dot_command_timeout() and an out-of-bounds memcpy_toio() that leaks kernel heap memory to the service processor. Fix with two guards: reject writes smaller than sizeof(struct dot_command_header) before allocation, then after copying user data reject commands where the buffer is smaller than the total size declared by the header (sizeof(header) + command_size + data_size). This ensures all subsequent header and payload field accesses stay within the buffer. Fixes: 1da177e ("Linux-2.6.12-rc2") Reported-by: Yuhao Jiang Cc: stable@vger.kernel.org Signed-off-by: Tyllis Xu Link: https://patch.msgid.link/20260314165355.548119-1-LivelyCarpet87@gmail.com Signed-off-by: Greg Kroah-Hartman Changed files: drivers/misc/ibmasm/ibmasmfs.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=a672682d39dd34e2b5ba4feb436723bed65125ff ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45994 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45994 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:N/A:L The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L 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: 2 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).