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CVE-2026-64546
drm/edid: fix OOB read in drm_parse_tiled_block()
Published 2026-07-27 (3 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-2026-64546 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-4720-1 · 2026-08-05 · text | 6.1.180-1 | Update the kernel and reboot. DLA-4720-1 shipped the fix on 2026-08-05, in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6405-1 · 2026-07-31 · text | 6.12.100-1 | Update the kernel and reboot. DSA-6405-1 shipped the fix on 2026-07-31, in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4724-1 · 2026-08-07 · text | 6.12.100-1~deb12u1 | Update the kernel and reboot. DLA-4724-1 shipped the fix on 2026-08-07, in 6.12.100-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
drm_parse_tiled_block() casts the DisplayID block to a struct displayid_tiled_block and reads the full fixed layout up to tile->topology_id[7] without checking block->num_bytes. The DisplayID iterator only validates the declared payload length, so a crafted EDID can advertise a tiled-display block (tag DATA_BLOCK_TILED_DISPLAY, or DATA_BLOCK_2_TILED_DISPLAY_TOPOLOGY for v2.0) with a small num_bytes at the end of a DisplayID extension. The read then runs past the end of the exact-sized kmemdup()'d EDID allocation, a heap out-of-bounds read. Reject blocks shorter than the spec's 22-byte tiled payload before reading the fixed struct, as drm_parse_vesa_mso_data() already does. BUG: KASAN: slab-out-of-bounds in drm_edid_connector_update Read of size 2 at addr ffff888010077700 by task exploit/147 dump_stack_lvl (lib/dump_stack.c:94 ...) print_report (mm/kasan/report.c:378 ...) kasan_report (mm/kasan/report.c:595) drm_edid_connector_update (drivers/gpu/drm/drm_edid.c:7581) bochs_connector_helper_get_modes (drivers/gpu/drm/tiny/bochs.c:574) drm_helper_probe_single_connector_modes (drivers/gpu/drm/drm_probe_helper.c:426) status_store (drivers/gpu/drm/drm_sysfs.c:219) ... vfs_write (fs/read_write.c:595 fs/read_write.c:688) ksys_write (fs/read_write.c:740)
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_edid.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
- 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
- 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
- 2026-07-27 (3 months ago)source
- CVSS
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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 |
|---|---|---|
| 3.19 | 5.10.261 | c4ab04ca1bbf |
| 3.19 | 5.15.212 | 9acd5c1ddc17 |
| 3.19 | 6.1.178 | 157727131ce8 |
| 3.19 | 6.6.145 | bfa05d89dc3c |
| 3.19 | 6.12.97 | 4f5484d25f85 |
| 3.19 | 6.18.40 | 9cc0f8e63e8c |
| 3.19 | 7.1.5 | 4137e1ecec9c |
| 3.19 | 7.2 | faaa1e115583 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4724-1 | 2026-08-07 | bookworm 6.12.100-1~deb12u1 | tracker |
| DLA-4723-1 | 2026-08-07 | bullseye 6.1.180-1~deb11u1 | tracker |
| DLA-4720-1 | 2026-08-05 | bookworm 6.1.180-1 | tracker |
| DLA-4717-1 | 2026-08-05 | bullseye 5.10.262-1 | tracker |
| DSA-6405-1 | 2026-07-31 | trixie 6.12.100-1 | 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 crafted EDID reaches the parser through a local device node — an unprivileged DRM client supplying a raw EDID buffer via the exynos vidi `DRM_AUTH` ioctl, or root via the connector's debugfs `edid_override` plus a sysfs re-probe. No network path exists, and local ioctl delivery is the lowest-friction vector (a physically attached malicious monitor/dock is an additional, equally automatic route).
- AC:LAttack complexity, low
- The attacker fully controls the EDID bytes and only needs to place a tiled-display DisplayID block with a small `num_bytes` at the tail of the last extension block; `drm_edid_valid()` checks nothing but the header and checksums, which the attacker computes. No race and no memory-layout precondition is needed to trigger the read.
- PR:LPrivileges required, low
- Handing an arbitrary EDID to `drm_edid_connector_update()` via `DRM_IOCTL_EXYNOS_VIDI_CONNECTION` requires only an authenticated DRM client (`DRM_AUTH`), i.e. an ordinary logged-in user with access to /dev/dri — no CAP_SYS_ADMIN and no root.
- UI:NUser interaction, none
- The attacker drives the connector probe itself through the ioctl, and on the hotplug path the EDID is read and parsed automatically by the kernel. No victim action is involved.
- S:UScope, unchanged
- The out-of-bounds read stays within the kernel's own heap and the impact is confined to the kernel security authority; no hypervisor, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- Up to ~21 bytes of adjacent slab memory are read past the exact-size EDID allocation, and eight of those bytes are persisted into the connector's tile fields and handed back to userspace in the TILE property blob via `DRM_IOCTL_MODE_GETPROPBLOB`, giving a repeatable heap-content leak usable to defeat KASLR or recover neighbouring object data.
- I:NIntegrity impact, none
- The defect is purely a read; `drm_mode_create_tile_group()` copies the OOB source into a properly sized destination, so no out-of-bounds write or control-flow corruption occurs.
- A:HAvailability impact, high
- The read runs past the end of the slab object and, for exact-fit allocations at a slab boundary, can touch unmapped memory; on KASAN or panic_on_warn kernels it is an immediate fatal report, and the resulting garbage tile geometry is propagated to the modesetting path.