From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-93061][MODERATE REGULAR] gpu: host1x: Avoid stack over-read in debug output helpers [ Upstream Date: Thu, 17 Sep 2026 16:39:09 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-93061 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: 3 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: d7a560dc912756fd8b39b28b10818d931e863d2d List-Id: CVE: CVE-2026-93061 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: gpu: host1x: Avoid stack over-read in debug output helpers [ Upstream Commit: d7a560dc912756fd8b39b28b10818d931e863d2d Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d7a560dc912756fd8b39b28b10818d931e863d2d Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93061 Analysis date: Thu, 17 Sep 2026 16:39:09 -0400 ActionableScore: 3 ActionableScore lower bound: unknown 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-2026-93061 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93061 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-2026-93061 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-93061 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:N';CWE-126;CWE-125;*CWE-200;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '4.7';DESCR 'A stack over-read in the host1x debug output helpers can occur because vsnprintf returns the length that would have been produced, not the number of bytes actually stored in the 256 byte stack buffer. That length is then passed to the debugfs output callback, so a long formatted debug line can make debugfs read past the end of the stack buffer and expose adjacent kernel memory. For the CVSS the PR:L is used for the paranoid score because some systems may expose debugfs or selected debugfs files to a less privileged local user or service account, although PR:H is typical when debugfs is restricted to administrators. The issue is not network reachable and requires local access to the affected debugfs interface on a system using the host1x driver. Impact is primarily confidentiality through possible kernel memory disclosure, with no evidence of memory write, privilege escalation, or system crash.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) YES PRINTF-TTY SIMPLEFIX HARDWARE DEBUGFS LINUS NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 3 * Conservative score: 3 * Raw paranoid score: 3 * Paranoid score: 3 * Final recommended bucket: **Borderline / manual review recommended**:: No floor or cap changed the score. 2. Signal breakdown Positive signals: * +1 Limited stack OOB read. `vsnprintf()` returned the would-have-written length, and that length could exceed the 256 byte stack buffer. * +1 User-visible disclosure path. The inflated length is passed to the debugfs output callback, which can emit bytes past the end of `o->buf`. * +1 Practical confidentiality consequence. Adjacent kernel stack bytes may be exposed through debugfs if a host1x debug output string exceeds the buffer. Negative or non-awarded signals: * Controlled reclaim not demonstrated. * Arbitrary write not demonstrated. * UAF not demonstrated. * Privilege escalation not demonstrated. * Reliable kernel crash not demonstrated. * Remote reachability not established. * No extra availability point, because the issue is disclosure-oriented rather than crash-oriented. * No CLASS_A substantial disclosure, because the leak appears limited, debugfs-specific, and dependent on unusually long debug output. * No host-admin penalty applied, because host-admin-equivalent access is not positively established from the supplied evidence. Debugfs access is deployment-dependent. 3. Reachability analysis The affected sink is debugfs output for the host1x driver. The attacker would need local access to the relevant debugfs files and a system using host1x. Typical debugfs deployments are restricted, but the supplied input does not prove that host-admin-equivalent privilege is always required for the complete read path, so `HostAdminRequired=UNKNOWN`. This is not network reachable. It is not namespace-scoped. No prior host setup is proven beyond the presence of the host1x driver and debugfs exposure. Special hardware or platform support is relevant because host1x is a GPU/display host controller subsystem, but this alone is not scored as rare hardware. The trigger also depends on a debug output call producing more than 256 bytes, which the commit says is very unlikely in practice. 4. Primitive and severity interpretation The exact primitive is a bounded stack over-read caused by using `vsnprintf()` return semantics as an output length. The stale or corrupted object model does not apply here. There is no UAF, no repeated release/refcount mutation, and no active structured stale object. The demonstrated consequence is potential kernel stack memory disclosure through debugfs. The speculative consequence would be use of leaked kernel data to assist another exploit, but no such chain is established by the patch. This remains `PrimitiveClass=CLASS_C` because the issue is a limited OOB read/info leak path rather than controlled corruption or a strong security-boundary bypass. `ImportantCandidate=NO` because there is no strong exploitation primitive, no LPE, no arbitrary read/write, and no demonstrated substantial kernel disclosure. `AutoDowngradeAllowed=YES` because the issue is constrained and does not leave unresolved kernel corruption leverage, but manual review is still recommended to confirm debugfs permissions and whether real output can exceed 256 bytes. Likely operational severity: Low to borderline Moderate, mainly confidentiality-only. 5. One-sentence report phrase A host1x debugfs output helper can pass an oversized length derived from vsnprintf to the debugfs sink, causing a limited stack over-read and possible local kernel memory disclosure when an unusually long debug line is generated. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Manual review should confirm actual debugfs permissions, host1x deployment exposure, and whether any real debug output path can reliably exceed 256 bytes. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: gpu: host1x: Avoid stack over-read in debug output helpers [ Upstream Commit: d7a560dc912756fd8b39b28b10818d931e863d2d Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d7a560dc912756fd8b39b28b10818d931e863d2d Changed files: drivers/gpu/host1x/debug.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=d7a560dc912756fd8b39b28b10818d931e863d2d ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93061 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93061 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:H/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:N The Best / paranoid CVSS score: 4.7 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: unknown Paranoid ActionableScore: 3 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).