[CVE-2026-98607][MODERATE REGULAR] drm/virtio: fix object leaks in virtio_gpu_resource_create_blob_ioctl() [ Upstream

[CVE-2026-98607][MODERATE REGULAR] drm/virtio: fix object leaks in virtio_gpu_resource_create_blob_ioctl() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-98607
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/virtio: fix object leaks in virtio_gpu_resource_create_blob_ioctl() [ Upstream
Commit: 73ea38a89b923fa08047885a0845d1cd89261ead
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=73ea38a89b923fa08047885a0845d1cd89261ead
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98607
Analysis date: Mon, 19 Oct 2026 01:19:08 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
Incorrect GEM cleanup on two virtio-gpu blob creation error paths prevents final object destruction and leaks guest and host-side resources, but reliable attacker-controlled accumulation or host-wide denial of service is not established.

======================================================================
ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98607 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98607

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-2026-98607	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98607 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE AEGIS_AS=1 LEGACY=MODERATE RESULT=SAME V39_AEGIS_ONE_STEP_UP=LOW->MODERATE (final reconciliation agrees; DECISION: both MODERATE)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H';*CWE-401;*CWE-772;CWE-404;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:L';BEST CVSS score: '5.6';DESCR 'virtio_gpu_resource_create_blob_ioctl() used drm_gem_object_release() instead of dropping its owned GEM reference when UUID assignment or GEM handle creation failed. The final object free callback therefore did not run, leaking the virtio GPU object, its resource ID, and the associated host side resource. For the CVSS the PR:L is selected because a local process with access to the DRM render device can invoke the affected ioctl without requiring full administrative privileges. The issue is not directly network reachable. The demonstrated impact is persistent resource retention rather than memory corruption. Repeated and controllable failures could potentially exhaust guest or host side virtio GPU resources and cause denial of service, but reliable accumulation is not established by the available code context. Confidentiality and integrity remain unaffected because no UAF, OOB access, information disclosure, or write primitive is present. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 5.6 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were final reconciliation stage LOW to MODERATE because KP specialist did not establish a qualifying panic and the cross model evidence reconciliation rule was applied. 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. Exact triggered rule markers were KPANIC_UNSUPPORTED_REMOVED and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. 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 MODERATE. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	MAYBE	VIRT SIMPLEFIX LEAK ERRORPATH HARDWARE LINUS KPANIC_UNSUPPORTED_REMOVED V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED	-	-	checked

======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=1
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
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 owned reference, so the final free callback does not run and the `virtio_gpu_object`, resource ID, and host-side resource remain allocated.

Negative signals:

* None. No privilege, race, hardware, or configuration penalty is justified by the supplied evidence.

Material non-awarded signals:

* No additional resource-exhaustion point. Repeated, attacker-controlled accumulation sufficient for guest-wide or host-wide exhaustion is not established.
* No local-unprivileged-trigger point. Render-node ioctl access is plausible, but the supplied context does not establish that a below-host-admin actor can reliably force either relevant error branch.
* No cross-boundary isolation point. A host-side resource is leaked, but host exhaustion or isolation bypass is not demonstrated.
* No UAF, OOB access, double release, stale dereference, arbitrary write, disclosure, authorization bypass, or privilege escalation is established.
* NEW52 B5-R does not apply. There is no heap OOB write, retry-accumulated index, or subsequent consumption of corrupted state.
* NEW53 B3-PENDING does not apply. There is no write to shared or file-backed storage.
* V33 and V32 do not apply. No attacker-influenced active structured-state corruption or checksum metadata write exists.

## 3. Reachability analysis

The affected function is a virtio-gpu DRM ioctl handler. A process with access to the applicable DRM device can request blob-resource creation, but the vulnerable cleanup path is reached only if UUID assignment or GEM handle creation fails after object allocation.

The evidence does not establish whether an ordinary render-node user can deliberately and repeatedly force either failure. It also does not establish that host-administrator privileges are necessary. Therefore, `HostAdminRequired=UNKNOWN` and `RequiresHostUID0=UNKNOWN`.

No namespace-scoped capability chain, special physical hardware requirement, race, or timing window is shown. A virtio-gpu device and suitable blob-resource support are deployment prerequisites. The guest-to-host aspect is limited to retention of a host-side resource. A demonstrated host DoS or host-memory corruption primitive is absent.

## 4. Primitive and severity interpretation

The exact defect is a missing reference drop on two error paths. `drm_gem_object_release()` performs GEM release processing but does not replace the required `drm_gem_object_put()` that drops the caller-owned reference and permits `obj->funcs->free()` to execute.

This is a concrete persistent resource leak, not a post-lifetime access. The object remains referenced rather than becoming dangling, so `RealUAF=NO`. There is no first release followed by reuse or a second lifetime mutation on the same freed object.

`PrimitiveClass=NONE` is appropriate because no corruption, stale-object use, authorization violation, or independently useful security primitive is established. The demonstrated consequence is resource retention. Guest or host denial of service through repeated accumulation remains possible but unresolved because reliable attacker control of the required failures is not shown.

`ImportantCandidate=NO` because the patch establishes neither an Important-preserving corruption primitive nor a demonstrated cross-boundary exhaustion mechanism. `AutoDowngradeAllowed=YES` because manual analysis would not lose an unresolved memory-corruption or authorization primitive.

## 5. One-sentence report phrase

Incorrect GEM cleanup on two virtio-gpu blob creation error paths prevents final object destruction and leaks guest and host-side resources, but reliable attacker-controlled accumulation or host-wide denial of service is not established.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm whether an unprivileged render-node client can deterministically force either error after host resource creation and repeat the operation sufficiently to exhaust host-side resources. If not, the issue can remain low priority and be automatically downgraded.

## 7. Call-site confidence

Call-site confidence: medium

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: drm/virtio: fix object leaks in virtio_gpu_resource_create_blob_ioctl() [ Upstream
Commit: 73ea38a89b923fa08047885a0845d1cd89261ead
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=73ea38a89b923fa08047885a0845d1cd89261ead

Changed files:
  drivers/gpu/drm/virtio/virtgpu_ioctl.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=73ea38a89b923fa08047885a0845d1cd89261ead

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98607 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98607

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:C/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.6

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: 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).