# CVE-2026-80618: drm/amdkfd: Avoid double-unpin of DOORBELL/MMIO BOs on free

> A local attacker can trigger a double-unpin error in the AMD KFD driver, causing a kernel warning and potential system instability.

- **Severity:** Not scored
- **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:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** BELL-CVE-2026-80618, DEBIAN-CVE-2026-80618, GHSA-82jr-fm8v-cx8j, UBUNTU-CVE-2026-80618

## What is CVE-2026-80618?

CVE-2026-80618 is an use after free vulnerability in Linux, published on 28 Aug 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/amdkfd: Avoid double-unpin of DOORBELL/MMIO BOs on free

amdgpu_amdkfd_gpuvm_free_memory_of_gpu() unpinned DOORBELL and MMIO
remap BOs (which are pinned at allocation time) before checking whether
the BO is still mapped to the GPU. When the BO is still mapped, the
function returns -EBUSY and leaves the BO alive, but it has already
been unpinned. The BO is then unpinned again when it is finally freed
during process teardown, triggering a ttm_bo_unpin() underflow warning:

  WARNING: CPU: 18 PID: 15066 at ttm/ttm_bo.c:650 amdttm_bo_unpin+0x6d/0x80 [amdttm]
  Workqueue: kfd_process_wq kfd_process_wq_release [amdgpu]
  RIP: 0010:amdttm_bo_unpin+0x6d/0x80 [amdttm]
  Call Trace:
   amdgpu_bo_unpin+0x1a/0x90 [amdgpu]
   amdgpu_amdkfd_gpuvm_unpin_bo+0x31/0xb0 [amdgpu]
   amdgpu_amdkfd_gpuvm_free_memory_of_gpu+0x3bf/0x460 [amdgpu]
   kfd_process_free_outstanding_kfd_bos+0xd4/0x170 [amdgpu]
   kfd_process_wq_release+0x109/0x1b0 [amdgpu]
   process_one_work+0x1e2/0x3b0
   worker_thread+0x50/0x3a0
   kthread+0xdd/0x100
   ret_from_fork+0x29/0x50

Move the unpin after the mapped_to_gpu_memory check so it only happens
once we are committed to freeing the BO.

(cherry picked from commit 927c5b2defb9b09856444d94bebfd056a002bd75)

## Which versions are affected by CVE-2026-80618?


## How do I fix CVE-2026-80618?

Apply the vendor's patch.

## Is CVE-2026-80618 being exploited?

There is no known exploitation of CVE-2026-80618 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80618 and fix it if it is affected.

What it is: CVE-2026-80618 is an use after free vulnerability in Linux, published on 28 Aug 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-2026-80618 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-2026-80618/ (Markdown: https://insights.sbomify.com/CVE-2026-80618/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80618
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80618
- OSV: https://osv.dev/vulnerability/CVE-2026-80618

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80618/
Summaries are generated and may contain mistakes; the official description above is the record.