CVE-2026-89801 drm/nouveau/uvmm: fix premature region free on failed OP_UNMAP_SPARSE
A use-after-free in the Linux kernel nouveau driver allows attackers to execute arbitrary code or escalate privileges via a failed sparse unmap operation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89801?
CVE-2026-89801 is a high-severity use after free vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
drm/nouveau/uvmm: fix premature region free on failed OP_UNMAP_SPARSE
In nouveau_uvmm_bind_job_submit()'s OP_UNMAP_SPARSE arm, op->reg is set from nouveau_uvma_region_find(), which only looks the region up and takes no reference; a region's sole reference is its membership in uvmm->region_mt. Two failure paths leave op->reg set: the -ENOENT check when the region is busy, and the drm_gpuvm_sm_unmap_ops_create() failure. The sibling nouveau_uvmm_sm_unmap_prepare() failure just below clears op->reg; these two do not.
unwind_continue steps back one op, so the failing op is skipped by the unwind loop and its op->reg stays set. nouveau_uvmm_bind_job_cleanup() then enters its if (op->reg) branch and calls nouveau_uvma_region_remove() and nouveau_uvma_region_put() on it, dropping the tree's sole reference and freeing a region this job never created. The comment above the cleanup loop documents the broken invariant: op->reg must be NULL on submit failure.
This frees a live region on an unrelated failure, reachable single-job when drm_gpuvm_sm_unmap_ops_create() returns -ENOMEM; if another job owns the same region, its cleanup then removes and puts the freed region, a use-after-free. Clear op->reg on both failure paths.
Which versions are affected by CVE-2026-89801?
How do I fix CVE-2026-89801?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-89801 being exploited?
There is no known exploitation of CVE-2026-89801 in the wild and no public exploit code.
Sources
Also known as AZL-101661, BELL-CVE-2026-89801, DEBIAN-CVE-2026-89801, GHSA-8x7w-6563-2c2q, UBUNTU-CVE-2026-89801.