[CVE-2026-99002][IMPORTANT] drm/vmwgfx: validate pitch coming from userspace [ Upstream

[CVE-2026-99002][IMPORTANT] drm/vmwgfx: validate pitch coming from userspace [ Upstream

[AL-KERNEL]

CVE: CVE-2026-99002
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: drm/vmwgfx: validate pitch coming from userspace [ Upstream
Commit: db6fbc2b77849e3c3c2bc115ea9ac925c4625a0d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=db6fbc2b77849e3c3c2bc115ea9ac925c4625a0d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99002
Analysis date: Mon, 26 Oct 2026 22:17:10 -0400
ActionableScore: 6
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
A low-privileged vmwgfx command can combine user-controlled copy parameters with erroneous typed-pointer stride arithmetic to write source pixels beyond the heap-allocated cursor snooper image.

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

The original Linux kernel CVE announcement for CVE-2026-99002 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99002

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: IMPORTANT
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-99002	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2026-99002 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=IMPORTANT RESULT=DIFF INDEPENDENT_LEGACY=IMPORTANT INDEPENDENT_RESULT=DIFF TEMP_KPANIC_MERGE=IMPORTANT_WINS_DISAGREEMENT PRE_MERGE_LEGACY=IMPORTANT (final Legacy and Aegis differ; FINAL: IMPORTANT, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H';CWE-125;*CWE-20;CWE-190;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H';BEST CVSS score: '7.1';DESCR 'vmwgfx cursor snooping used a userspace controlled DMA pitch to calculate the source address for each copied row lacking validation against the backing buffer size. A malformed pitch can move later reads beyond the mapped buffer object and cause an out of bounds kernel read. This can plausibly crash the guest kernel and may expose limited adjacent data through the generated cursor image, but the patch does not establish an arbitrary read or any write primitive. For the CVSS the PR:L value reflects that a local process must have access to the vmwgfx DRM interface and submit the crafted command. The issue is not directly network reachable and there is no supported guest to host primitive. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 7.1 and the production ActionableScore returned 6 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to IMPORTANT because the CVSS score, vector or bug class threshold rule was applied. final reconciliation stage IMPORTANT to IMPORTANT because KP specialist did not establish a qualifying panic. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist produced a review artifact and its decision was processed by the applicable downgrade and preservation rules. Exact triggered rule markers were INCREASED_TO_HIGH_BASED_ON_GUESSCVSS and TEMP_KPANIC_MERGE_IMPORTANT_WINS and KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 4.0 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is IMPORTANT.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 6)	MAYBE	OOB DMAorINTERRUPT HARDWARE LINUS INCREASED_TO_HIGH_BASED_ON_GUESSCVSS TEMP_KPANIC_MERGE_IMPORTANT_WINS KPANIC_UNSUPPORTED_REMOVED	-	-	checked

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

ActionableScore=6
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 6.
* Conservative score: 6; no floor or cap applied.
* Raw paranoid score: 6.
* Paranoid score: 6; no additional speculative effects awarded.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +2 — Strong corruption primitive: `srf->snooper.image` has element size `pitchBytesPerBlock`, but the old loop advances it by `i * image_pitch` elements rather than bytes/pixels. The fix changes this to `i * VMW_CURSOR_SNOOP_WIDTH`, showing an attacker-influenced heap destination-stride OOB write.
* +2 — Strong exploit leverage: each `memcpy` writes source-buffer bytes, while userspace influences the box dimensions, pitch, and DMA source. The overwrite occurs at predictable excessive row offsets, although no arbitrary target or named adjacent object is shown.
* +1 — Below-host-admin local trigger: supplied evidence identifies a low-privileged process with vmwgfx DRM access submitting the crafted command.
* +1 — Plausible kernel crash from heap overwrite or the separately documented source OOB read.
* No confidentiality point: cursor-image disclosure of adjacent data is plausible but no read-back path or specific disclosed bytes are established.
* No integrity point beyond the corruption primitive: no protected adjacent victim is identified.
* NEW52/B5-R does not apply: no retry-accumulated index is involved.
* No UAF, controlled reclaim, callback overwrite, LPE, authorization bypass, remote reachability, or extra availability effect is shown.

3. Reachability analysis

The supported actor is a local, below-host-admin process granted access to the vmwgfx DRM command interface; host UID 0 is not required by the supplied evidence. Exact device-node/render-node permissions and namespace capability scope are not shown, so namespace-scoped reachability remains unknown. No network path, special race, retry sequence, or separate vulnerability is required. vmwgfx availability is a deployment prerequisite, but the evidence does not justify a rare-hardware penalty.

4. Primitive and severity reading

The patch fixes both source validation and a distinct destination-stride error. Because `image` elements are one pixel wide, using byte pitch as an element index advances each destination row too far and can write beyond the snooper image allocation. This is an attacker-influenced heap OOB write, hence CLASS_A, not the read-only CWE-125 issue described by the legacy summary. Payload and offsets are materially influenced, but arbitrary write, selected adjacent victim, confidentiality impact, and privilege escalation remain unproven. The concrete write requires mandatory Important-class review and prevents automatic downgrade.

5. One-sentence report phrase

A low-privileged vmwgfx command can combine user-controlled copy parameters with erroneous typed-pointer stride arithmetic to write source pixels beyond the heap-allocated cursor snooper image.

6. Manual review advice

MANUAL CHECK REQUIRED

Confirm the snooper-image allocation layout, maximum accepted box dimensions, DRM-node access model, and whether predictable adjacent objects provide practical exploitation leverage.

7. Call-site confidence

Call-site confidence: high

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

Patch: drm/vmwgfx: validate pitch coming from userspace [ Upstream
Commit: db6fbc2b77849e3c3c2bc115ea9ac925c4625a0d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=db6fbc2b77849e3c3c2bc115ea9ac925c4625a0d

Changed files:
  drivers/gpu/drm/vmwgfx/vmwgfx_kms.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=db6fbc2b77849e3c3c2bc115ea9ac925c4625a0d

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

The original Linux kernel CVE announcement for CVE-2026-99002 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99002

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:L/PR:L/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
  The Best / paranoid CVSS score: 7.1

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: 6

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: IMPORTANT
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): IMPORTANT

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).