# 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.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-101661, BELL-CVE-2026-89801, DEBIAN-CVE-2026-89801, GHSA-8x7w-6563-2c2q, UBUNTU-CVE-2026-89801

## 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.

## Is CVE-2026-89801 being exploited?

There is no known exploitation of CVE-2026-89801 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89801 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-89801 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-89801/ (Markdown: https://insights.sbomify.com/CVE-2026-89801/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89801
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89801
- OSV: https://osv.dev/vulnerability/CVE-2026-89801

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89801/
Summaries are generated and may contain mistakes; the official description above is the record.