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CVE-2026-68255
drm/virtio: bound EDID block reads to the response buffer
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-2026-68255 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-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. 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
virtio_get_edid_block() validates the read offset only against the device-supplied resp->size field, never against the fixed-size resp->edid array. The EDID block index is driven by the device-supplied extension count, so a malicious virtio-gpu backend can advertise a large size together with a high block count and read far past the array into adjacent kernel memory, which is then surfaced in the parsed EDID (an out-of-bounds read / info leak). Also reject any read whose end exceeds the size of the edid array. Conforming EDID responses stay within the array and are unaffected.
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/virtio/virtgpu_vq.c
- What this is
- VIRTIO GPU DRIVERMAINTAINERS section matched on drivers/gpu/drm/virtio/ · dri-devel@lists.freedesktop.org · Maintained
- Kernel module
- virtio_gpu
Check it on the machine
grep -w CONFIG_DRM_VIRTIO_GPU /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 virtio_gpuPrints 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
- trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_DRM_VIRTIO_GPU
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
- 2026-08-10 (2 months ago)source
- CVSS
- 7.7 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.19%, higher than 7.9% 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 |
|---|---|---|
| 5.0 | 5.10.266 | 65ce911f341a |
| 5.0 | 5.15.217 | 64bedd2758ec |
| 5.0 | 6.1.183 | 3f506a85a905 |
| 5.0 | 6.6.148 | 9fc2a017c5d5 |
| 5.0 | 6.12.101 | 2757e6e80309 |
| 5.0 | 6.18.42 | 35be0e2c6862 |
| 5.0 | 7.1.6 | 375c1934ef01 |
| 5.0 | 7.2 | 4e1a53892ba7 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | 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 attacker is a malicious or compromised virtio-gpu backend (host/hypervisor device emulation or a vhost-user device process) supplying crafted EDID responses over the virtqueue; this is device-to-guest-kernel access, not remote network access.
- AC:LAttack complexity, low
- The device fully controls resp->size, the EDID extension count and the timing of the read by raising VIRTIO_GPU_EVENT_DISPLAY config-change interrupts, so it can trigger the out-of-bounds read reliably and repeatedly with no conditions outside its control.
- PR:NPrivileges required, none
- No guest credentials are needed at all: the vulnerable path runs in the virtio-gpu probe and the config-changed workqueue in kernel context, driven purely by device responses.
- UI:NUser interaction, none
- EDID re-reads are initiated automatically at probe and on device-raised display events; no guest user has to open, mount or interact with anything.
- S:UScope, unchanged
- The out-of-bounds read and the resulting disclosure both occur within the guest kernel's own security authority; no IOMMU, VM or sandbox boundary is crossed by the impact itself.
- C:HConfidentiality impact, high
- Block indices up to 255 give start offsets of ~32 KB past the 1024-byte resp->edid array, reading far beyond the kmalloc'd response object into adjacent kernel heap memory, which is then surfaced as parsed EDID via the connector blob property and world-readable sysfs edid file, and hex-dumped for bad blocks.
- I:NIntegrity impact, none
- Destination buffers in _drm_do_get_edid() are allocated from the block count, so the flaw is strictly an over-read of the response buffer with no out-of-bounds write or kernel data modification.
- A:HAvailability impact, high
- The memcpy can walk tens of kilobytes past the slab object into unmapped or guarded memory, causing an oops/panic (and an immediate BUG under KASAN/hardened builds), and the device can repeat it at will.