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CVE-2026-80582
drm/shmem_helper: Check VMA boundaries for PMD mappings
Published 2026-08-26 (2 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-2026-80582 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 | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
In the ->huge_fault handler do not install a PMD huge page mapping if the huge page exceeds the boundaries of the VMA. All other ->huge_fault handlers have similar checks and the resulting mapping will trigger a VM_BUG_ON_VMA() if it ever reaches copy_pmd_range().
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_shmem_helper.c
- What this is
- DRM DRIVERS AND MISC GPU PATCHESMAINTAINERS section matched on drivers/gpu/drm/ · Maintained
- Kernel module
- drm_shmem_helper
Check it on the machine
grep -w CONFIG_DRM_GEM_SHMEM_HELPER /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 drm_shmem_helperPrints 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
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_DRM_GEM_SHMEM_HELPER
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
- 2026-08-26 (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
- 0.17%, higher than 5.3% 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 |
|---|---|---|
| 7.0 | 7.1.10 | 12803e89a1e5 |
| 7.0 | 7.2 | 617bbd087148 |
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
- Reachable via local mmap/page-fault on DRM GEM shmem buffers (drm_gem_mmap -> drm_gem_shmem_any_fault -> try_insert_pfn PMD path), used by virtio-gpu, panfrost, lima, v3d, panthor, and other GPU/accelerator drivers on phones, VMs, and desktops.
- AC:LAttack complexity, low
- An attacker controls GEM buffer size, mmap length, fault addresses, and follow-on fork/mprotect; no race or rare layout is required beyond creating a non-PMD-aligned mapping near a VMA end so a 2MB PMD install overruns the VMA.
- PR:LPrivileges required, low
- Only standard local GPU access is needed (open /dev/dri/renderD* or card*, DRM GEM create/mmap ioctls); no CAP_SYS_ADMIN or init-namespace root, matching unprivileged desktop render-group users, Android GPU apps, and cloud/VM GPU workloads.
- UI:NUser interaction, none
- Exploitation is fully attacker-driven through their own DRM client (create buffer, mmap, touch pages, fork); no separate victim action such as opening a file or mounting a filesystem is required.
- S:UScope, unchanged
- Impact stays within the kernel/GPU process security boundary (local memory corruption and kernel panic); it does not cross VM/host, IOMMU, or sandbox authority boundaries.
- C:HConfidentiality impact, high
- Without the VMA boundary check, a 2MB PMD PFNMAP can cover virtual/physical pages beyond the GEM object and VMA, creating out-of-bounds read primitives from adjacent mapped memory before copy_pmd_range() trips VM_BUG_ON_VMA().
- I:HIntegrity impact, high
- The same oversized PMD mapping installs writable PFNMAP entries beyond the allocated buffer, enabling out-of-bounds writes and corrupt page tables exploitable for control-flow or data tampering, not merely a clean fault.
- A:HAvailability impact, high
- The invalid PMD eventually hits VM_BUG_ON_VMA() in copy_pmd_range() or __split_huge_pmd() (e.g., fork of the mapping), producing a kernel BUG/oops and panic as demonstrated in related drm/shmem_helper THP testing.