# CVE-2026-74520: iommu/iommufd: Fix IOPF group ownership UAF

> A use-after-free in the Linux kernel IOMMUFD subsystem allows attackers to execute arbitrary code or escalate privileges via crafted IOPF group handling.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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:** 15 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-74520, DEBIAN-CVE-2026-74520, GHSA-9qch-cxwm-9cjc, UBUNTU-CVE-2026-74520

## What is CVE-2026-74520?

CVE-2026-74520 is a high-severity use after free vulnerability in Linux, published on 15 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:

iommu/iommufd: Fix IOPF group ownership UAF

iopf_group_alloc() links each last-page IOPF group into the generic IOPF
pending list before invoking the domain fault handler.
iommufd_fault_iopf_handler() also queued an accepted group in the
IOMMUFD deliver list without removing it from the generic pending list.

When detach or HWPT replacement drops the device's IOPF reference count
to zero, an IOMMU driver may call iopf_queue_remove_device(). That
function responds to and frees groups through the generic pending list
without removing the same groups from IOMMUFD's deliver list or response
xarray. A later read, response, or cleanup can then access the freed
group and cause a UAF.

Fix this by dequeuing an accepted group from the generic pending list
before IOMMUFD queues it for userspace response.
Make iopf_group_response() send a response regardless of pending-list
membership, so the dequeued group can still be completed by IOMMUFD.

## Which versions are affected by CVE-2026-74520?


## How do I fix CVE-2026-74520?

Apply the vendor's patch.

## Is CVE-2026-74520 being exploited?

There is no known exploitation of CVE-2026-74520 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74520 and fix it if it is affected.

What it is: CVE-2026-74520 is a high-severity use after free vulnerability in Linux, published on 15 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-2026-74520 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-2026-74520/ (Markdown: https://insights.sbomify.com/CVE-2026-74520/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74520
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74520
- OSV: https://osv.dev/vulnerability/CVE-2026-74520

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74520/
Summaries are generated and may contain mistakes; the official description above is the record.