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CVE-2026-68236
drm/amd/display: set new_stream to NULL after release
Published 2026-08-10 (2 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-2026-68236 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 | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.101-1 | Update the kernel and reboot. Fixed in 6.12.101-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4745-1 · 2026-08-18 · text | 6.12.101-1~deb12u1 | Update the kernel and reboot. DLA-4745-1 shipped the fix on 2026-08-18, in 6.12.101-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
In dm_update_crtc_state(), the skip_modeset path releases new_stream via dc_stream_release() but does not set the pointer to NULL. If a later error (e.g., color management failure) triggers the fail label, the error path calls dc_stream_release() again on the same dangling pointer, causing a double release and potential use-after-free. Fix this by setting new_stream to NULL after the initial release. (cherry picked from commit 99f3af19073b3ddbfd96e789124cce12c4277b28)
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/display/amdgpu_dm/amdgpu_dm.c
- What this is
- AMD DISPLAY COREMAINTAINERS section matched on drivers/gpu/drm/amd/display/ · amd-gfx@lists.freedesktop.org · Supported
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid, bookworm · linux-6.12?
- ?
- not established - no Makefile entry for the affected file
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.
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
Signals
- Published
- 2026-08-10 (2 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
- 0.13%, higher than 2.0% 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 |
|---|---|---|
| 4.15 | 5.10.271 | 92b7c6e3a154 |
| 4.15 | 5.15.222 | bf9c06c70f49 |
| 4.15 | 6.1.189 | 01ba5b36898d |
| 4.15 | 6.6.148 | ba8bf1dcbb44 |
| 4.15 | 6.12.101 | 5182e442e613 |
| 4.15 | 6.18.42 | 679f23f0a360 |
| 4.15 | 7.1.6 | 0676fecbb524 |
| 4.15 | 7.2 | 9fa26b9eed61 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4745-1 | 2026-08-18 | bookworm 6.12.101-1~deb12u1 | tracker |
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 bug is reached through the DRM atomic modeset ioctl (DRM_IOCTL_MODE_ATOMIC) on a local /dev/dri/card* node of an AMD GPU; there is no network or remote input path into dm_update_crtc_state().
- AC:LAttack complexity, low
- A single atomic commit that requests a mode change while attaching a wrong-sized DEGAMMA_LUT blob deterministically drives amdgpu_dm_check_crtc_color_mgmt() to -EINVAL and hits the double dc_stream_release(); no race and no uncontrolled precondition, and TEST_ONLY commits let the attacker repeat it freely to groom the heap.
- PR:LPrivileges required, low
- The atomic ioctl is gated only by DRM master on the card node, which any unprivileged local user on a graphical seat or an unused VT can hold; no CAP_SYS_ADMIN or root is needed.
- UI:NUser interaction, none
- The attacker performs the whole sequence with its own ioctl calls; no action by another user or administrator is required, and TEST_ONLY commits do not even disturb the display.
- S:UScope, unchanged
- The corrupted dc_stream_state and the resulting freed-memory reuse stay within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- The extra kref_put() frees the dc_stream_state while the CRTC state and the DC context still reference it; reading through those dangling pointers after the slab is reallocated leaks adjacent kernel object contents and pointers, and the attacker can spray to control what lands there.
- I:HIntegrity impact, high
- The reference-count underflow yields a use-after-free/double-free: subsequent kref_put() writes into reallocated slab memory and dc_stream_free() kfree()s an attacker-influenced update_scratch pointer, giving write and arbitrary-free primitives usable for privilege escalation.
- A:HAvailability impact, high
- Even without exploitation the premature free causes dereference of freed stream/sink/link structures during atomic state unwind, producing a kernel oops or panic and killing the display pipeline; it can be triggered repeatedly.