# 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.

- **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:** 6 May 2026
- **Updated:** 19 Oct 2026
- **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, UBUNTU-CVE-2026-43278

## 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 (Double Free)

## Which versions are affected by CVE-2026-43278?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43278?

Apply the vendor's patch.

## 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

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43278 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-43278 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-43278/ (Markdown: https://insights.sbomify.com/CVE-2026-43278/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43278
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43278
- OSV: https://osv.dev/vulnerability/CVE-2026-43278

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43278/
Summaries are generated and may contain mistakes; the official description above is the record.