From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-74445][MODERATE REGULAR] drm/vmwgfx: reject DX_BIND_QUERY without a DX context Date: Sat, 15 Aug 2026 12:19:27 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-74445 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: 7eae011829f94a76470ec76f016805f508437755 List-Id: CVE: CVE-2026-74445 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: drm/vmwgfx: reject DX_BIND_QUERY without a DX context Commit: 7eae011829f94a76470ec76f016805f508437755 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7eae011829f94a76470ec76f016805f508437755 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74445 Analysis date: Sat, 15 Aug 2026 12:19:27 -0400 ActionableScore: 4 ActionableScore lower bound: 3 Actionable bucket: Borderline Moderate / Actionable Moderate candidate Manual review required: NO Summary: A local userspace process with access to a vmwgfx render node can submit a malformed DX_BIND_QUERY execbuf without a DX context, triggering a NULL pointer dereference and kernel oops, with impact limited to denial of service based on the patch evidence. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74445 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74445 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-74445 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:N/I:N/A:H';**CWE-476;*CWE-20;CWE-754;BEST CVSS score: '5.5';DESCR 'A NULL pointer dereference in the vmwgfx execbuf path can occur because vmw_cmd_dx_bind_query dereferences the DX context node even when no DX context was provided. A local userspace process with access to a vmwgfx render node can trigger this by submitting an execbuf with dx_context_handle set to SVGA3D_INVALID_ID and a SVGA_3D_CMD_DX_BIND_QUERY command. For the CVSS the PR:L because the attacker needs local code execution and access to the render node fd, but does not need full administrative privileges in typical render node deployments. The issue is not network reachable and is triggered through a local DRM ioctl command stream. Impact is denial of service via kernel oops or crash. The patch context supports a NULL dereference rather than UAF or arbitrary memory corruption, so confidentiality and integrity are not raised for the paranoid score.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Moderate / Actionable Moderate candidate (with actual score 4) YES NULLPTR SIMPLEFIX HARDWARE LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: 3 * Paranoid score: 4 * Final recommended bucket: **Borderline Moderate / Actionable Moderate candidate** ## 2. Signal breakdown * Local unprivileged trigger: +1 Any local userspace process with access to a vmwgfx render-node fd can submit the malformed execbuf. * Reliable kernel crash / strong DoS: +1 The commit explicitly describes a NULL pointer dereference and kernel oops via `sw_context->dx_ctx_node->ctx`. * Broad/default/common subsystem or broadly deployed exposure: +1 This is not a universal Linux path, but vmwgfx render nodes are commonly exposed in VMware guest deployments where this driver is used. * Paranoid only: Availability impact realistic: +1 The trigger appears simple and repeatable from a local render-node fd. If the environment treats oops as fatal or if repeated oopses destabilize the host guest kernel, availability impact is stronger. Not applied: * No generic memory corruption bonus. The patch supports NULL dereference, not UAF, OOB write, double-free, object reuse, or arbitrary write. * No privilege escalation bonus. No reclaim, callback control, type confusion, writable stale object, or controlled corruption primitive is shown. * No remote/network bonus. Trigger is local DRM ioctl/execbuf, not packet or network input. ## 3. Reachability analysis The bug is reachable by local userspace through the vmwgfx DRM execbuf path when a render-node fd is available. In typical graphical or virtualized VMware guest environments, render nodes may be accessible to non-root users, so PR-like practical reachability is local unprivileged rather than admin-only. Namespaces and containers may matter if `/dev/dri/renderD*` is passed into a container. Without device access, the bug is not reachable. The path is not network reachable and requires the vmwgfx driver and relevant virtual GPU stack. Call-site confidence: high, because the patch and commit describe the exact dereference and the malformed command stream condition. ## 4. Severity interpretation This behaves like a local denial-of-service issue, not an Important-class memory corruption vulnerability. The theoretical risk is limited because the primitive is a NULL pointer dereference rather than attacker-controlled memory corruption. Realistic exploitation evidence supports kernel oops/crash only. The issue should not be treated as a strong LPE candidate based on the supplied patch. It is still worth manual review in affected VMware guest environments because render-node exposure can make the crash reachable by ordinary local users. ## 5. One-sentence report phrase A local userspace process with access to a vmwgfx render node can submit a malformed DX_BIND_QUERY execbuf without a DX context, triggering a NULL pointer dereference and kernel oops, with impact limited to denial of service based on the patch evidence. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: local unprivileged render-node reachability plus reliable kernel oops makes this worth review for exposed vmwgfx deployments, but the patch does not support UAF, arbitrary corruption, or privilege escalation. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/vmwgfx: reject DX_BIND_QUERY without a DX context Commit: 7eae011829f94a76470ec76f016805f508437755 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7eae011829f94a76470ec76f016805f508437755 Commit description: vmw_cmd_dx_bind_query() unconditionally dereferences sw_context->dx_ctx_node->ctx. Userspace can trigger a NULL pointer dereference from any render-node fd by submitting an execbuf with dx_context_handle == SVGA3D_INVALID_ID and a SVGA_3D_CMD_DX_BIND_QUERY opcode in the command stream: dx_ctx_node is left NULL and the kernel oopses on the assignment. The same NULL is then re-read in vmw_resources_reserve() via vmw_context_get_dx_query_mob(). All sibling DX handlers fail-close on a missing dx_ctx_node using VMW_GET_CTX_NODE(). Use the same pattern here, returning -EINVAL up front before any relocation state is published. Fixes: 9c079b8 ("drm/vmwgfx: Adapt execbuf to the new validation api") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4.7 Signed-off-by: Zack Rusin Reviewed-by: Ian Forbes Link: https://patch.msgid.link/20260505222728.519626-3-zack.rusin@broadcom.com Signed-off-by: Greg Kroah-Hartman Changed files: drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.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=7eae011829f94a76470ec76f016805f508437755 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74445 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74445 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: Not available The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 5.5 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).