From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80662][MODERATE REGULAR] cxl: Fix CXL_HEADERLOG_SIZE to match RAS Capability size [ Upstream Date: Fri, 28 Aug 2026 04:38:02 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80662 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: 6fc1919a6f2ed541484dd1f6cd93374044f8fd3d List-Id: CVE: CVE-2026-80662 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: cxl: Fix CXL_HEADERLOG_SIZE to match RAS Capability size [ Upstream Commit: 6fc1919a6f2ed541484dd1f6cd93374044f8fd3d Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6fc1919a6f2ed541484dd1f6cd93374044f8fd3d Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80662 Analysis date: Fri, 28 Aug 2026 04:38:02 -0400 ActionableScore: 4 ActionableScore lower bound: 3 Actionable bucket: Borderline. Manual review recommended Manual review required: YES Summary: A CXL RAS header log size mismatch can cause the kernel to copy about 448 bytes past a valid 64 byte stack embedded header log into a trace event, exposing kernel stack data to userspace readers of trace data. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80662 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80662 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-2026-80662 MODERATE 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:H/I:N/A:L';CWE-125;CWE-126;*CWE-200;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.3';DESCR 'A CXL RAS header log size mismatch can make the kernel copy 512 bytes where only 64 bytes of real header log data exist. In the CPER path the source header_log is embedded in a stack local structure, so the trace event memcpy can read about 448 bytes past the valid field and place kernel stack data into the trace ring buffer. For the CVSS the PR:L is used because exploitation requires local access to tracefs or another local consumer of trace data, not full kernel code execution. The issue is not network reachable and normally requires a CXL RAS or CPER error event plus trace data access. Impact is primarily information disclosure through kernel stack exposure, with possible low availability concern from out of range MMIO reads. No direct privilege escalation primitive is proven, but the stack disclosure is concrete and should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline. Manual review recommended (with actual score 4) SKIP CVE-2026-80662 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE DANGER INIT ERRORPATH LOG HARDWARE 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. Manual review recommended**:: ## 2. Signal breakdown Triggered signals: * Firmware-mediated external influence: +1 The vulnerable path depends on CXL RAS or CPER error reporting, which can be influenced by CXL hardware or firmware error conditions rather than ordinary local syscalls alone. * Confidentiality impact plausible: +1 The commit explicitly describes a 512 byte trace event memcpy from a source where only 64 bytes are valid, causing about 448 bytes of kernel stack data to be copied into the trace ring buffer. * Practical exploit chain demonstrated or strongly implied: +1 The chain is concrete: oversized header log size -> stack overread in CPER caller -> trace event ring buffer -> userspace readable via tracefs or tracing consumer. Paranoid-only signal: * Privileged kernel device management disclosure path: +1 This is not a strong memory corruption primitive, but the bug is in trusted CXL RAS error handling and exposes kernel stack bytes through a kernel tracing ABI. This justifies manual review sensitivity. Not awarded: * Remote reachable: +0 No realistic direct network trigger is shown. * Local unprivileged trigger: +0 Reading tracefs and reliably triggering CXL RAS or CPER events is not generally available to an arbitrary unprivileged user. * Generic memory corruption: +0 This is an out-of-bounds read and stack disclosure, not OOB write, UAF, double free, or type confusion. * Strong DoS: +0 The MMIO overread may be undesirable, but the primary demonstrated impact is information disclosure, not a reliable crash. Possible reductions considered: * Rare hardware condition: not applied in the main score CXL hardware is configuration dependent, but the bug exposes real kernel stack data through a standard tracing path when the subsystem is present. Applying a full rare-hardware penalty would likely understate triage value. Call-site confidence: high. The relevant copy paths and trace event layout are included in the supplied patch. ## 3. Reachability analysis The issue is reachable when the system has CXL RAS or CPER error handling active and an uncorrectable CXL protocol error is traced. The attacker needs access to trace output or to a local tracing consumer such as tracefs or a daemon that reads these events. In typical deployments, tracefs access is restricted to root or tracing-privileged users, so this is not a default unprivileged local trigger. Containers do not normally gain this access unless tracing interfaces are delegated or exposed by the host. The trigger is not network reachable. A malicious or faulty device or firmware could help produce the error event, but that is better modeled as firmware-mediated influence rather than remote reachability. ## 4. Severity interpretation This behaves like an actionable information disclosure issue, not an ordinary low-risk cleanup. The patch fixes a concrete out-of-bounds read where kernel stack bytes can be copied into a userspace-observable trace buffer. Realistic exploitation evidence supports confidentiality impact, mainly kernel stack disclosure. It does not support arbitrary write, UAF, type confusion, direct privilege escalation, or remote exploitation. The paranoid score is higher only because stack disclosure can assist later exploitation and because the leak path is concrete enough to deserve manual review. ## 5. One-sentence report phrase A CXL RAS header log size mismatch can cause the kernel to copy about 448 bytes past a valid 64 byte stack embedded header log into a trace event, exposing kernel stack data to userspace readers of trace data. ## 6. Manual review recommendation MANUAL CHECK REQUIRED. YES REQUIRES MANUAL CHECK. Reason: this is a concrete kernel stack information disclosure through trace events, even though exploitation depends on CXL error generation and tracefs or tracing-consumer access. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: cxl: Fix CXL_HEADERLOG_SIZE to match RAS Capability size [ Upstream Commit: 6fc1919a6f2ed541484dd1f6cd93374044f8fd3d Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6fc1919a6f2ed541484dd1f6cd93374044f8fd3d Changed files: drivers/cxl/core/ras.c drivers/cxl/core/trace.h drivers/cxl/cxl.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=6fc1919a6f2ed541484dd1f6cd93374044f8fd3d ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80662 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80662 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:L/I:N/A:N The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:L The Best / paranoid CVSS score: 5.3 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).