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CVE-2026-63854
drm/amdgpu/vcn: set no_user_fence for VCN v3.0 enc/dec rings
Published 2026-07-19 (3 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-2026-63854 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
VCN encoder and decoder rings do not support 64-bit user fence writes, reject CS submissions with user fences. (cherry picked from commit 663bed3c7b8b9a7624b0d95d300ddae034ad0614)
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
- 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
- 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
- 2026-07-19 (3 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.18%, higher than 6.6% 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 |
|---|---|---|
| 5.9 | 6.6.141 | e74fc9c72c1b |
| 5.9 | 6.12.91 | 26c4f38529ac |
| 5.9 | 6.18.33 | 2d6525e7b250 |
| 5.9 | 7.0.10 | b076e45e6f75 |
| 5.9 | 7.1 | f1e5a6660d7c |
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_AMDGPU_CS on a local AMDGPU render node (/dev/dri/renderD*); this is a local ioctl path, not a network-reachable interface.
- AC:LAttack complexity, low
- An attacker with render-node access can reliably submit a command stream with AMDGPU_CHUNK_ID_FENCE targeting VCN v3.0 encoder/decoder rings without races or uncontrollable system state.
- PR:LPrivileges required, low
- The vulnerable amdgpu_cs_ioctl path requires only authenticated render-node access (DRM_AUTH|DRM_RENDER_ALLOW), which is available to unprivileged local users on typical Linux systems with AMDGPU hardware.
- UI:NUser interaction, none
- No victim interaction is required; the attacker directly submits the malformed GPU command stream via ioctl from their own process.
- S:UScope, unchanged
- The vulnerability operates within the attacker's own AMDGPU/GPU context and does not cross a demonstrated security boundary such as VM escape or IOMMU bypass.
- C:HConfidentiality impact, high
- Allowing unsupported 64-bit user fence submissions on VCN rings causes GPU-initiated memory writes with incorrect semantics; this class of GPU memory corruption can be leveraged for information disclosure.
- I:HIntegrity impact, high
- The bug permits GPU DMA writes to attacker-influenced virtual addresses through malformed user-fence handling, constituting a memory corruption primitive that could enable further exploitation.
- A:HAvailability impact, high
- Malformed fence operations on VCN rings can hang the video engine or trigger GPU reset, causing denial of service affecting graphics and compute availability on the system.