Look up another CVE · open CVE-2026-89818 in the interactive tracker
CVE-2026-89818
drm/amdgpu/vcn: fix integer overflow in dec_msg buffer count check
Published 2026-09-16 (33 days 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-2026-89818 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-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
If the supplied msg[2] (num_buffers) is 0x3FFFFFFF, the expression 6 + num_buffers * 4 wraps to 2 and the bounds check passes, letting the parser loop far past the end of the message BO. Triggering it additionally requires a ~4GiB mapping so that msg[1] survives the earlier "header does not fit in BO" check. Rewrite the test in division form, which is overflow-free by construction. Also update the message to reflect that msg is invalid.
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/amd/amdgpu/vcn_v3_0.c
drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c
- What this is
- RADEON and AMDGPU DRM DRIVERSMAINTAINERS section matched on drivers/gpu/drm/amd/ · amd-gfx@lists.freedesktop.org · Supported
- Kernel module
- amdgpu
Check it on the machine
grep -w CONFIG_DRM_AMDGPU /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 amdgpuPrints 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
- trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_DRM_AMDGPU
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
- 2026-09-16 (33 days ago)source
- CVSS
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.16%, higher than 4.7% 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 |
|---|---|---|
| 6.1.175 | 6.1.188 | c2340281be4d |
| 6.6.140 | 6.6.157 | 6dceaeceaa7c |
| 6.12.90 | 6.12.110 | 47799e1f893d |
| 6.18.32 | 6.18.51 | 7e28853c78c2 |
| 7.1 | 7.2.5 | 9ae19bd60891 |
| 7.1 | 7.3 | 4d7390530853 |
| 5.15.209 | 0 | 0 |
| 6.1.175 | 0 | 0 |
| 6.6.140 | 0 | 0 |
| 6.12.90 | 0 | 0 |
| 6.18.32 | 0 | 0 |
| 7.0.9 | 0 | 0 |
| 7.0.9 | 0 | 0 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | 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
- The bug is reached only via the local DRM_IOCTL_AMDGPU_CS ioctl on /dev/dri/renderD* (amdgpu_cs_ioctl → amdgpu_cs_patch_jobs → amdgpu_cs_patch_ibs → vcn_v3/v4_0_ring_patch_cs_in_place → vcn_*_dec_msg). There is no network or physical path to the VCN decode-message parser.
- AC:LAttack complexity, low
- The attacker fully controls the decode-message GEM BO. Setting num_buffers to 0x3FFFFFFF with a ~4GiB mapping makes 6+num_buffers*4 wrap to 2 so the uint32 bounds check passes deterministically; allocating that mapping is attacker-controlled on typical GPU workstations and cloud GPU hosts.
- PR:LPrivileges required, low
- AMDGPU_CS is registered with DRM_AUTH|DRM_RENDER_ALLOW, so any unprivileged local user who can open the AMDGPU render node (typical render/video group on desktops, handhelds, Android, and GPU cloud instances) can submit VCN command buffers without root.
- UI:NUser interaction, none
- The attacker submits the crafted VCN command buffer through their own DRM context; no separate victim action such as opening a file or mounting a filesystem is required.
- S:UScope, unchanged
- The out-of-bounds read is performed by the CPU in the kernel kmap of the message BO and stays within the kernel security authority; it is not a VM escape or IOMMU/DMA boundary bypass.
- C:HConfidentiality impact, high
- Bypassing the buffer-count check lets the parser loop about 0x3FFFFFFF times, each step reading 16 bytes past the kmapped BO, an unbounded kernel out-of-bounds read well beyond a few bytes.
- I:NIntegrity impact, none
- The loop only reads message dwords and, when a CREATE record is seen, still bounds-checks offset/size against the BO before any further access; no out-of-bounds write or control-flow hijack primitive is produced.
- A:HAvailability impact, high
- The unbounded walk past the kmapped BO into unmapped kernel or MMIO address space causes a page fault/oops, and the billion-iteration loop can also soft-lock the CS path before faulting.