Description
In the Linux kernel, the following vulnerability has been resolved:

drm/vmwgfx: enforce cursor size limits for MOB cursors

vmw_cursor_plane_atomic_check() bounds cursor width and height only
on the legacy update path; the SVGA_CAP2_CURSOR_MOB path -- the
default on modern hosts -- accepts any size. When the requested size
exceeds SVGA_REG_CURSOR_MAX_DIMENSION or SVGA_REG_MOB_MAX_SIZE,
vmw_cursor_mob_get() returns -EINVAL and leaves vps->cursor.mob NULL.
Its return value is then discarded in vmw_cursor_plane_prepare_fb(),
so the subsequent vmw_cursor_update_mob() calls
vmw_bo_map_and_cache(NULL) and oopses inside
vmw_bo_map_and_cache_size() on the tbo.base.size load.

Reachable from any DRM master via DRM_IOCTL_MODE_CURSOR2 with a
sufficiently large width or height (e.g. cursor_max_dim + 1).

Reject oversized cursors in atomic_check for both MOB-backed cursor
update types. The MOB byte-size limit only applies to the
SVGA_CAP2_CURSOR_MOB path (vmw_cursor_mob_size() returns 0 for
GB_ONLY); compute the required MOB size in 64-bit to avoid overflow
when very large dimensions are requested.

In prepare_fb only call vmw_cursor_mob_get()/_map() for
VMW_CURSOR_UPDATE_MOB -- the GB_ONLY path uses bo->map.virtual
directly and would otherwise be silently downgraded to NONE on hosts
without SVGA_CAP2_CURSOR_MOB (where vmw_cursor_mob_get() always
returns -EINVAL). Degrade the update to NONE if vmw_cursor_mob_get()
or vmw_cursor_mob_map() fails so the update path does not run with a
NULL backing MOB.
Published: 2026-08-28
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The bug arises in the VMware GPU driver (vmwgfx) when creating or resizing a cursor. The atomic check routine only validates cursor size on a legacy path, while the default modern path (SVGA_CAP2_CURSOR_MOB) allows any width or height. When a size larger than the hardware limits is requested via DRM_IOCTL_MODE_CURSOR2, the call to vmw_cursor_mob_get() returns an error, but the error is ignored downstream, leading a null cursor object to be dereferenced and causing a kernel oops. This results in an unhandled exception that crashes the kernel, effectively rebooting the machine and denying service. Affected systems include any Linux kernel build that incorporates the vmwgfx DRM driver, regardless of distribution, as the vulnerability resides in the core kernel module. The specific kernel version is not enumerated in the data, but any pre‑patch build that still contains the unbounded cursor size logic is vulnerable. Users running VMware host or guest systems that expose the cursor API will be impacted. Risk and exploitability are high because the flaw is exploitable by any process with DRM master privileges, which typically requires local root or a user with access to the graphics device. The EPSS score is not available, and the flaw is not listed in the CISA KEV catalog; however, the CVSS assessment is implicitly high due to the crash potential. The attack vector is local, through the DRM_IOCTL_MODE_CURSOR2 ioctl, and an attacker can trigger the crash by sending an oversized cursor size.

Affected Systems

Linux kernels that include the vmwgfx DRM driver are affected. No specific version numbers are listed, meaning all builds containing the unbounded cursor handling code before the listed patch are vulnerable. Users running VMware products that expose the DRM cursor API on these kernels should consider the vulnerability.

Risk and Exploitability

The vulnerability is not in the CISA KEV catalog, and the EPSS score is unavailable, but it carries a high CVSS score inferred from the kernel crash impact. It can be triggered locally by any process with DRM master rights using DRM_IOCTL_MODE_CURSOR2, leading to a denial of service by rebooting the host.

Generated by OpenCVE AI on August 28, 2026 at 10:33 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply the kernel patch that enforces cursor size limits in vmwgfx
  • If a patch is not yet available, restrict the DRM_IOCTL_MODE_CURSOR2 ioctl to privileged users or disable cursor updates entirely in the VM configuration
  • Configure all applications that use custom cursors to enforce a maximum size that aligns with the hardware limits to avoid accidental oversized requests

Generated by OpenCVE AI on August 28, 2026 at 10:33 UTC.

Tracking

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Advisories

No advisories yet.

History

Fri, 28 Aug 2026 11:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-190
CWE-20
CWE-476

Fri, 28 Aug 2026 07:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: drm/vmwgfx: enforce cursor size limits for MOB cursors vmw_cursor_plane_atomic_check() bounds cursor width and height only on the legacy update path; the SVGA_CAP2_CURSOR_MOB path -- the default on modern hosts -- accepts any size. When the requested size exceeds SVGA_REG_CURSOR_MAX_DIMENSION or SVGA_REG_MOB_MAX_SIZE, vmw_cursor_mob_get() returns -EINVAL and leaves vps->cursor.mob NULL. Its return value is then discarded in vmw_cursor_plane_prepare_fb(), so the subsequent vmw_cursor_update_mob() calls vmw_bo_map_and_cache(NULL) and oopses inside vmw_bo_map_and_cache_size() on the tbo.base.size load. Reachable from any DRM master via DRM_IOCTL_MODE_CURSOR2 with a sufficiently large width or height (e.g. cursor_max_dim + 1). Reject oversized cursors in atomic_check for both MOB-backed cursor update types. The MOB byte-size limit only applies to the SVGA_CAP2_CURSOR_MOB path (vmw_cursor_mob_size() returns 0 for GB_ONLY); compute the required MOB size in 64-bit to avoid overflow when very large dimensions are requested. In prepare_fb only call vmw_cursor_mob_get()/_map() for VMW_CURSOR_UPDATE_MOB -- the GB_ONLY path uses bo->map.virtual directly and would otherwise be silently downgraded to NONE on hosts without SVGA_CAP2_CURSOR_MOB (where vmw_cursor_mob_get() always returns -EINVAL). Degrade the update to NONE if vmw_cursor_mob_get() or vmw_cursor_mob_map() fails so the update path does not run with a NULL backing MOB.
Title drm/vmwgfx: enforce cursor size limits for MOB cursors
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-28T06:53:04.652Z

Reserved: 2026-08-26T14:34:25.786Z

Link: CVE-2026-80701

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-28T08:16:55.640

Modified: 2026-08-28T08:16:55.640

Link: CVE-2026-80701

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-28T10:45:04Z

Weaknesses
  • CWE-190

    Integer Overflow or Wraparound

  • CWE-20

    Improper Input Validation

  • CWE-476

    NULL Pointer Dereference