CVE-2026-43278 dm: clear cloned request bio pointer when last clone bio completes
A use-after-free vulnerability in the Linux kernel device-mapper allows attackers to trigger double-frees, potentially leading to code execution or system crashes.
- 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
What is CVE-2026-43278?
CVE-2026-43278 is a high-severity use after free vulnerability in Linux kernel, published on 6 May 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:
dm: clear cloned request bio pointer when last clone bio completes
Stale rq->bio values have been observed to cause double-initialization of cloned bios in request-based device-mapper targets, leading to use-after-free and double-free scenarios.
One such case occurs when using dm-multipath on top of a PCIe NVMe namespace, where cloned request bios are freed during blk_complete_request(), but rq->bio is left intact. Subsequent clone teardown then attempts to free the same bios again via blk_rq_unprep_clone().
The resulting double-free path looks like:
nvme_pci_complete_batch() nvme_complete_batch() blk_mq_end_request_batch() blk_complete_request() // called on a DM clone request bio_endio() // first free of all clone bios ... rq->end_io() // end_clone_request() dm_complete_request(tio->orig) dm_softirq_done() dm_done() dm_end_request() blk_rq_unprep_clone() // second free of clone bios
Fix this by clearing the clone request's bio pointer when the last cloned bio completes, ensuring that later teardown paths do not attempt to free already-released bios.
Weakness: CWE-415
Which versions are affected by CVE-2026-43278?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43278?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-43278 being exploited?
There is no known exploitation of CVE-2026-43278 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43278, DEBIAN-CVE-2026-43278, GHSA-vwc3-h3w8-q85f, ROOT-OS-DEBIAN-11-CVE-2026-43278, ROOT-OS-UBUNTU-2204-CVE-2026-43278, ROOT-OS-UBUNTU-2404-CVE-2026-43278 and 1 more.