Look up another CVE · open CVE-2026-63849 in the interactive tracker
CVE-2026-63849
drm/amdgpu/vcn: set no_user_fence for VCN v5.0.1 enc 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-2026-63849 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 | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| 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 e16be95a2c3ee712b142cb27d2dca0b461181359)
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_v5_0_1.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 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- 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
- 0.17%, higher than 6.3% 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 |
|---|---|---|
| 6.14 | 6.18.33 | 081ef0e46c9c |
| 6.14 | 7.0.10 | 5a4bffd67e94 |
| 6.14 | 7.1 | 8f4954722eab |
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 vulnerability is reached only through local DRM ioctls (primarily DRM_IOCTL_AMDGPU_CS on a /dev/dri/renderD* node), not over any network protocol.
- AC:LAttack complexity, low
- An attacker with render-node access can deterministically submit a VCN_ENC command buffer with an AMDGPU_CHUNK_ID_FENCE chunk; no race or attacker-uncontrollable conditions are required beyond having the affected AMDGPU hardware.
- PR:LPrivileges required, low
- Exploitation requires only local access to the GPU render node as an unprivileged user (DRM_AUTH|DRM_RENDER_ALLOW); no root or special capabilities are needed.
- UI:NUser interaction, none
- Triggering the bug requires only the attacker's own ioctl submissions; no action by another user or victim is required.
- S:UScope, unchanged
- Impact is confined to the attacker's GPU command-submission context and process GPU virtual address space; it does not cross a VM/host or other security-boundary scope.
- C:HConfidentiality impact, high
- The unsupported 64-bit user-fence path causes the VCN engine to perform GPU memory writes to attacker-influenced addresses, which constitutes exploitable memory corruption that can be leveraged for information disclosure.
- I:HIntegrity impact, high
- The malformed fence write gives the attacker a GPU-initiated arbitrary memory write primitive within their GPU VA space, which can corrupt adjacent buffers and be chained toward code execution.
- A:HAvailability impact, high
- Submitting unsupported user fences to the VCN ring can hang or reset the GPU and trigger kernel driver errors, causing denial of service on affected systems.