# CVE-2026-90324: ublk: check import_ubuf() return value

> A missing return value check in the Linux kernel ublk driver can lead to a null pointer dereference and system crash.

- **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:** 17 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-101900, BELL-CVE-2026-90324, DEBIAN-CVE-2026-90324, GHSA-9f96-m8pp-q99r, UBUNTU-CVE-2026-90324

## What is CVE-2026-90324?

CVE-2026-90324 is a high-severity vulnerability in Linux, published on 17 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:

ublk: check import_ubuf() return value

import_ubuf() can fail if the address range (provided by the userspace
ublk server) is outside the allowed user address space. Return that 0
bytes were copied if import_ubuf() fails rather than passing an
uninitialized struct iov_iter to ublk_copy_user_pages().

## Which versions are affected by CVE-2026-90324?


## How do I fix CVE-2026-90324?

Apply the vendor's patch.

## Is CVE-2026-90324 being exploited?

There is no known exploitation of CVE-2026-90324 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90324 and fix it if it is affected.

What it is: CVE-2026-90324 is a high-severity vulnerability in Linux, published on 17 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-2026-90324 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-2026-90324/ (Markdown: https://insights.sbomify.com/CVE-2026-90324/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90324
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90324
- OSV: https://osv.dev/vulnerability/CVE-2026-90324

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90324/
Summaries are generated and may contain mistakes; the official description above is the record.