# CVE-2026-99169: futex: Fix mm reuse handling for FUT_OFF_MMSHARED


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 28 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** AZL-111317, BELL-CVE-2026-99169, DEBIAN-CVE-2026-99169, GHSA-8p9g-5mhx-rvh4, UBUNTU-CVE-2026-99169

## What is CVE-2026-99169?

CVE-2026-99169 is a vulnerability in Linux, published on 28 Oct 2026. 

### Official description

In the Linux kernel, the following vulnerability has been resolved:

futex: Fix mm reuse handling for FUT_OFF_MMSHARED

A FUT_OFF_MMSHARED futex is a shared futex that refers to an MM.
It is possible for a process to wait on a shared futex with a different MM
because a FUT_OFF_INODE waiter can be requeued onto a FUT_OFF_MMSHARED
futex by another process.
This can cause FUT_OFF_MMSHARED waiters on a freed MM to consume
wakeups intended for a newly allocated MM at the same address.

Fix it by keying FUT_OFF_MMSHARED using a unique 64-bit per-MM ID.
Leave private futexes as before to avoid influencing the performance of the
hotpath.

(Multi-threaded processes typically implicitly use FUT_OFF_MMSHARED by
setting clear_child_tid such that it points into anonymous memory, which
causes mm_release() in a multi-threaded mm to perform FUTEX_WAKE.)

## Which versions are affected by CVE-2026-99169?


## How do I fix CVE-2026-99169?

Upgrade to a fixed version.

## Is CVE-2026-99169 being exploited?

There is no known exploitation of CVE-2026-99169 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99169 and fix it if it is affected.

What it is: CVE-2026-99169 is a vulnerability in Linux, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99169 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-99169/ (Markdown: https://insights.sbomify.com/CVE-2026-99169/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99169
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99169
- OSV: https://osv.dev/vulnerability/CVE-2026-99169

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99169/
Summaries are generated and may contain mistakes; the official description above is the record.