# CVE-2026-64509: rust: block: fix GenDisk cleanup paths

> A memory leak in the Linux kernel's Rust block layer can retain queue state, potentially leading to denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jul 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-64509, DEBIAN-CVE-2026-64509, GHSA-5653-8mcx-7p26, ROOT-OS-UBUNTU-2204-CVE-2026-64509, UBUNTU-CVE-2026-64509

## What is CVE-2026-64509?

CVE-2026-64509 is a memory corruption vulnerability in Linux, published on 25 Jul 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:

rust: block: fix GenDisk cleanup paths

GenDiskBuilder::build() still has fallible work after
__blk_mq_alloc_disk(), but its error path only recovers the
foreign queue data. That leaks the temporary gendisk and
request_queue until later teardown. If the caller moved the last
Arc<TagSet<T>> into build(), the leaked queue can retain blk-mq
state after the tag set is dropped.

Fix the pre-registration failure path by dropping the temporary
gendisk reference with put_disk() before recovering queue_data,
so disk_release() can tear down the owned queue.

Also pair GenDisk::drop() with put_disk() after del_gendisk().
Once a Rust GenDisk has been added with device_add_disk(),
del_gendisk() only unregisters it; the final gendisk reference
still has to be dropped to complete the release path.

## Which versions are affected by CVE-2026-64509?


## How do I fix CVE-2026-64509?

Apply the vendor's patch.

## Is CVE-2026-64509 being exploited?

There is no known exploitation of CVE-2026-64509 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64509 and fix it if it is affected.

What it is: CVE-2026-64509 is a memory corruption vulnerability in Linux, published on 25 Jul 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-2026-64509 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-2026-64509/ (Markdown: https://insights.sbomify.com/CVE-2026-64509/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64509
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64509
- OSV: https://osv.dev/vulnerability/CVE-2026-64509

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64509/
Summaries are generated and may contain mistakes; the official description above is the record.