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

Not scored Published 25 Jul 2026 Updated 17 Aug 2026

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

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

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.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-64509 being exploited?

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

Sources

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.