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CVE-2026-63844
drm/amdgpu/jpeg: set no_user_fence for JPEG v4.0.3 ring
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem drivers/gpu. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-63844 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| 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
JPEG rings do not support 64-bit user fence writes, reject CS submissions with user fences. (cherry picked from commit 2f6afc97d259d530f4f86c7743efbc573a8da927)
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/jpeg_v4_0_3.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. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- 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
- ?
- not established - no Makefile entry for the affected file
- M
- a module where it is built at all; some flavours do not build it
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- 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
- unimportantsource
- 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 |
|---|---|---|
| 6.5 | 6.6.141 | b884ff67d62e |
| 6.5 | 6.12.91 | d6bd2a5fd611 |
| 6.5 | 6.18.33 | 8549b3933038 |
| 6.5 | 7.0.10 | 249fa7549736 |
| 6.5 | 7.1 | 83e37c0987ca |
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 local access to the AMDGPU DRM render node and the DRM_IOCTL_AMDGPU_CS ioctl path; there is no network, adjacent-wireless, or physical-access entry point to the vulnerable JPEG ring submission code.
- AC:LAttack complexity, low
- An attacker with render-node access can deterministically submit a command stream to the VCN JPEG ring with an AMDGPU_CHUNK_ID_FENCE user-fence chunk; no race or attacker-uncontrollable memory layout is required beyond having affected VCN 4.0.3 hardware.
- PR:LPrivileges required, low
- The vulnerable amdgpu_cs_ioctl handler is gated by DRM_AUTH|DRM_RENDER_ALLOW, requiring a local unprivileged user with access to /dev/dri/renderD* (typically the render/video group), not root or capabilities obtainable only in the init namespace.
- UI:NUser interaction, none
- Once the attacker has render-node access, triggering the bug is fully programmatic via ioctl/GEM setup and does not require any additional victim interaction such as opening files or mounting filesystems.
- S:UScope, unchanged
- Impact is confined to the AMDGPU driver/GPU memory domain of the submitting process's security context; this is not a KVM guest-to-host escape, IOMMU bypass, or other cross-authority boundary crossing.
- C:HConfidentiality impact, high
- Incorrect 64-bit user-fence handling on JPEG hardware can cause GPU-initiated writes to unintended addresses in GPU-visible memory, a memory-corruption primitive that can be leveraged for arbitrary kernel/GPU memory disclosure beyond the intended fence buffer.
- I:HIntegrity impact, high
- The bug allows the GPU to perform unintended memory writes when processing user-fence completion on a ring that lacks 64-bit user-fence support, providing a writable corruption primitive that could be developed into further code execution or privilege escalation.
- A:HAvailability impact, high
- Submitting unsupported user fences to the JPEG v4.0.3 ring can hang or reset the GPU/firmware and trigger repeated denial of service on affected AMD systems (workstations, laptops, cloud GPU instances) using VCN 4.0.3.