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CVE-2026-74443
drm/vmwgfx: bound DMA command body size against suffix pointer
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/gpu. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-74443 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
vmw_cmd_dma() locates the DMA suffix at (unsigned long) &cmd->body + header->size - sizeof(*suffix) without checking that header->size is large enough to contain both cmd->body and the suffix. An undersized header makes the suffix pointer underflow back into the previous command in the bounce buffer. The verifier later writes suffix->maximumOffset, clobbering verified fields of an already-relocated earlier command -- a TOCTOU on the device-visible command stream that lets one command rewrite another's GMR id, surface id, or other authenticated fields. Reject the command if the body is too small for the suffix to fit.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
- What this is
- DRM DRIVER FOR VMWARE VIRTUAL GPUMAINTAINERS section matched on drivers/gpu/drm/vmwgfx/ · dri-devel@lists.freedesktop.org · Supported
- Kernel module
- vmwgfx
Check it on the machine
grep -w CONFIG_DRM_VMWGFX /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w vmwgfxPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le
- trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_DRM_VMWGFX
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/gpu
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.33 | 5.10.265 | eb20f418933b |
| 2.6.33 | 5.15.216 | fcd1e56e7816 |
| 2.6.33 | 6.1.183 | a4a37080a5ac |
| 2.6.33 | 6.6.151 | 036e16ada953 |
| 2.6.33 | 6.12.103 | d5d7ada4e129 |
| 2.6.33 | 6.18.44 | 7e40e6120fb2 |
| 2.6.33 | 7.1.8 | 9759da60e38d |
| 2.6.33 | 7.2 | f4f1db96bfd6 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- Exploitation requires issuing DRM_IOCTL_VMW_EXECBUF with a crafted SVGA command batch via /dev/dri/card* or /dev/dri/renderD*, the standard local DRM render-node path for the vmwgfx driver in VMware virtual machines.
- AC:LAttack complexity, low
- The attacker fully controls execbuf command layout and can set an undersized SVGA_3D_CMD_SURFACE_DMA header->size so the suffix pointer underflows into the prior command; no races, rare configs, or victim-dependent heap layout are required.
- PR:LPrivileges required, low
- VMW_EXECBUF is registered with DRM_RENDER_ALLOW, so any local user with access to the DRM render node (typically membership in the render/video group on VMware guests) can reach vmw_cmd_dma without real root in the init namespace.
- UI:NUser interaction, none
- No victim interaction is required beyond the attacker opening the DRM device and submitting a malicious execbuf ioctl; exploitation does not depend on another user mounting filesystems or performing other actions.
- S:CScope, changed
- The bug is a TOCTOU on the device-visible SVGA command stream: verifier writes clobber already-checked fields (GMR id, surface id, DMA bounds) in the bounce buffer before submission to the VMware virtual GPU, bypassing guest/host isolation enforced by command authentication.
- C:HConfidentiality impact, high
- Rewriting authenticated GMR/surface identifiers or inflating maximumOffset can authorize SVGA surface DMA reads (including SVGA3D_READ_HOST_VRAM) beyond validated guest buffer bounds, yielding arbitrary guest memory disclosure and plausible host VRAM reads via the virtual device backend.
- I:HIntegrity impact, high
- Clobbering verified command fields lets a later command rewrite another's GMR id, surface id, or DMA limit so the hypervisor executes unauthorized SVGA3D_WRITE_HOST_VRAM or guest GMR DMA, enabling arbitrary memory write and code-execution primitives typical of kernel heap corruption.
- A:HAvailability impact, high
- Corrupting the bounce-buffer command stream before FIFO submission can panic the guest kernel (invalid SVGA commands/resources) and enables repeatable denial of service; memory corruption in the verifier path is independently rated High per kernel CVSS guidance.