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CVE-2026-63885
drm/gem: fix race between change_handle and handle_delete
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-2026-63885 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 | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
drm_gem_change_handle_ioctl leaves the old handle live in the IDR during the window between spin_unlock(table_lock) and the final spin_lock(table_lock). A concurrent drm_gem_handle_delete on the old handle succeeds in this window, decrements handle_count to 0, and frees the GEM object while the new handle's IDR entry still references it. NULL the old handle's IDR entry before dropping table_lock so that any concurrent GEM_CLOSE on the old handle sees NULL and returns -EINVAL. Restore the old entry on the prime-bookkeeping error path.
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/drm_gem.c
- What this is
- DRM DRIVERS AND MISC GPU PATCHESMAINTAINERS section matched on drivers/gpu/drm/ · Maintained
- Kernel module
- drm
Check it on the machine
grep -w CONFIG_DRM /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 drmPrints 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
- trixieBnot built on amd64/cloud-amd64, arm64/cloud-arm64, 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
- B
- built in on some, a module on others, absent on the rest
- Build switch
- CONFIG_DRM
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
- 8.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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 |
|---|---|---|
| 6.18.32 | 6.18.35 | 0dfa42cfe4db |
| 7.0.9 | 7.0.12 | cde2c9257cbe |
| 7.1 | 7.1 | 7164d78559b0 |
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 ioctl calls on /dev/dri/renderD* or /dev/dri/card* through DRM_IOCTL_GEM_CHANGE_HANDLE and DRM_IOCTL_GEM_CLOSE; there is no network-facing path to this code.
- AC:LAttack complexity, low
- The attacker controls both racing threads from the same process (one issuing GEM_CHANGE_HANDLE, one issuing GEM_CLOSE on the old handle) and can repeat until the window is hit; this is a self-induced race, not one dependent on external timing.
- PR:LPrivileges required, low
- Only DRM_RENDER_ALLOW is required, available to unprivileged local users with access to a render node (common on desktops, Android, browsers' GPU processes, and cloud GPU instances); no CAP_SYS_ADMIN or init-namespace root is needed.
- UI:NUser interaction, none
- No victim interaction is required beyond the attacker already having render-node access; the race is triggered entirely by the attacker's own concurrent ioctl calls.
- S:CScope, changed
- Successful exploitation crosses from a sandboxed application security boundary (browser GPU process, Android app sandbox, or container with passed-through GPU device) into kernel memory, enabling privilege escalation beyond the attacker's original security scope.
- C:HConfidentiality impact, high
- The bug is a GEM object use-after-free; freed kernel heap objects can be reallocated and dereferenced via subsequent GEM operations, enabling arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- Use-after-free of a drm_gem_object allows heap grooming and corruption of reallocated objects, providing a standard path to arbitrary kernel write and local privilege escalation/code execution.
- A:HAvailability impact, high
- The race can free a GEM object still referenced by ioctl state, causing kernel oops/panic on dereference of freed memory; UAF bugs also carry inherent crash risk even before full exploitation.