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CVE-2026-63842
drm/amdgpu/jpeg: set no_user_fence for JPEG v5.0.0 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-2026-63842 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 0f43893d3cd478fa57836697525b338817c9c23d)
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_v5_0_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. 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 |
|---|---|---|
| 6.9 | 6.12.91 | 3a55ff19a6ff |
| 6.9 | 6.18.33 | a7e63bb93a7f |
| 6.9 | 7.0.10 | 69ab75c7c5f3 |
| 6.9 | 7.1 | ea7c61c5f895 |
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 submitting AMDGPU command buffers via DRM_IOCTL_AMDGPU_CS on a local /dev/dri/renderD* device; the JPEG ring is not reachable over the network.
- AC:LAttack complexity, low
- An attacker with render-node access can deterministically submit a CS with an AMDGPU_CHUNK_ID_FENCE chunk and a JPEG-ring IB (AMDGPU_HW_IP_VCN_JPEG); no race or external timing is required.
- PR:LPrivileges required, low
- The amdgpu_cs_ioctl path is gated by DRM_AUTH|DRM_RENDER_ALLOW, reachable by unprivileged local users with standard render-node access (render group membership), not root.
- UI:NUser interaction, none
- No victim interaction is required; the attacker triggers the malformed user-fence write through their own ioctl submission.
- S:UScope, unchanged
- Impact is confined to GPU memory writes within the attacker's amdgpu VM context; this is standard local privilege/resource abuse, not a VM escape or cross-authority boundary crossing.
- C:HConfidentiality impact, high
- The JPEG engine performs an unsupported 64-bit fence memory write (via jpeg_v4_0_3_dec_ring_emit_fence with AMDGPU_FENCE_FLAG_64BIT), causing GPU memory corruption that can be leveraged for arbitrary read primitives within the attacker's GPU address space.
- I:HIntegrity impact, high
- The malformed hardware fence write can corrupt arbitrary GPU-mapped buffers in the submitter's VM, providing a write primitive that could be developed into GPU code execution or further kernel compromise.
- A:HAvailability impact, high
- Incorrect fence handling can hang or reset the GPU (affecting all users of the device) and may trigger kernel GPU driver recovery paths, causing denial of service.