From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98609][LOW] drm/virtio: fix object leak when drm_gem_handle_create() fails [ Upstream Date: Mon, 19 Oct 2026 05:17:50 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98609 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 13423a058187c2039aa8cb235c916be4477221b7 List-Id: CVE: CVE-2026-98609 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: drm/virtio: fix object leak when drm_gem_handle_create() fails [ Upstream Commit: 13423a058187c2039aa8cb235c916be4477221b7 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=13423a058187c2039aa8cb235c916be4477221b7 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98609 Analysis date: Mon, 19 Oct 2026 05:17:50 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: An incorrect GEM cleanup operation leaks guest memory and host-side virtio GPU resources when handle creation fails, but reliable accumulation, memory corruption, and privilege escalation are not established. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98609 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98609 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: LOW 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-2026-98609 LOW https://www.kernelcve.org/list/?q=CVE-2026-98609 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=1 LEGACY=LOW RESULT=SAME (final reconciliation agrees; DECISION: both LOW) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;CWE-404;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'An incorrect reference cleanup in virtio_gpu_gem_create leaves a GEM object at refcount 1 when drm_gem_handle_create fails. The unreachable object retains its shmem pages, SG table, virtio GPU object, resource ID, and the corresponding host side resource because VIRTIO_GPU_CMD_RESOURCE_UNREF is never queued. For the CVSS the PR:L reflects that a local user or process needs access to the virtio GPU DRM device node. AC:H reflects the need to make the specific handle creation step fail after the backing object was successfully created and to repeat that condition for meaningful accumulation. The issue is not network reachable. The demonstrated impact is a persistent resource leak with low availability impact. A high availability impact is plausible only if the error path can be reached repeatedly enough to exhaust guest memory, resource identifiers, or host backend resources. There is no supported UAF, OOB access, information disclosure, arbitrary write, or privilege escalation primitive. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. No severity changing production threshold or specialist override was recorded. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 with primitive class CLASS_C and manual review RECOMMENDED. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE VIRT SIMPLEFIX LEAK ERRORPATH HARDWARE LINUS - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO ## 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 1 * Paranoid score: 1 * No floor or cap was applied. * Final recommended bucket: **Ordinary Moderate**:: ## 2. Signal breakdown Positive signals: * +1 Concrete persistent kernel resource/reference leak. Calling `drm_gem_object_release()` does not drop the reference owned by `virtio_gpu_gem_create()`. The unreachable object remains at refcount 1 and retains shmem pages, the SG table, the resource ID, the `virtio_gpu_object`, and the host-side virtio GPU resource. Negative signals: * No negative score was applied. Host-admin privilege, rare hardware, and difficult attacker-controlled triggering are not positively established and therefore are not used as penalties. Material non-awarded signals: * No UAF or repeated release exists. The defect prevents the final reference from being dropped rather than accessing an object after its lifetime ends. * No OOB read or write, controlled overwrite, arbitrary write, controlled reclaim, disclosure, authorization bypass, or privilege-escalation primitive is established. * No crash point is demonstrated. * An additional resource-exhaustion point is not awarded because reliable and repeatable control of the `drm_gem_handle_create()` failure path is not established. * B5-R does not apply because there is no retry-accumulated heap OOB write or later consumption of corrupted structured state. * B3-PENDING does not apply. Shmem pages are leaked, but no shared backing is modified. * V33 and V34 do not apply because no active structured state is corrupted and consumed by a privileged downstream component. * B4-PENDING does not apply because no authorization decision or DENY-to-ALLOW transition is involved. ## 3. Reachability analysis The vulnerable sequence requires `virtio_gpu_object_create()` to succeed and the following `drm_gem_handle_create()` operation to fail. A process with access to the relevant virtio GPU DRM node can reach GEM object creation, but the supplied evidence does not establish which node is exposed, whether an ordinary logged-in user has access, or whether that user can reliably force the specific handle-creation failure repeatedly. Accordingly, `HostAdminRequired` remains `UNKNOWN`. This is not evidence that host administration is required, but below-host-admin completion of the entire trigger is also not positively established. No namespace-scoped capability chain is shown. No network trigger or race exists. A virtio GPU device is required, but no rarity penalty is applied merely because the code is a virtual GPU driver. ## 4. Primitive and severity interpretation The exact defect is an ownership and reference-cleanup error producing a persistent resource leak. `drm_gem_object_release()` reverses GEM initialization but does not decrement the object reference count or invoke `obj->funcs->free`. Consequently, `virtio_gpu_free_object()` does not run and `VIRTIO_GPU_CMD_RESOURCE_UNREF` is not queued. This is not a stale-object use, double put, or post-lifetime mutation. The object remains alive and unreachable. Therefore, `RealUAF=NO` and `PrimitiveClass=NONE`. The demonstrated consequence is retention of guest-side memory and host-side virtio GPU resources. Availability degradation or exhaustion is plausible only if an actor can repeatedly force the narrow error path, which is unresolved. There is no basis for confidentiality, integrity, LPE, or Important-grade impact. Automatic downgrade is allowed because only a resource leak is established and no unresolved corruption or trust-boundary primitive remains. ## 5. One-sentence report phrase An incorrect GEM cleanup operation leaks guest memory and host-side virtio GPU resources when handle creation fails, but reliable accumulation, memory corruption, and privilege escalation are not established. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED The patch establishes only a persistent resource leak, while attacker-controlled repetition and host-wide exhaustion are not demonstrated. ## 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/virtio: fix object leak when drm_gem_handle_create() fails [ Upstream Commit: 13423a058187c2039aa8cb235c916be4477221b7 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=13423a058187c2039aa8cb235c916be4477221b7 Changed files: drivers/gpu/drm/virtio/virtgpu_gem.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=13423a058187c2039aa8cb235c916be4477221b7 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98609 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98609 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:N/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H 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: 1 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: LOW KPANIC detected for this report: NO Published priority for this report (same as in Subject): LOW 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).