# CVE-2026-80758: futex: Avoid private hash use-after-free on final put

> A use-after-free in the Linux kernel futex subsystem allows local attackers to cause denial of service or potentially escalate privileges.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-80758, DEBIAN-CVE-2026-80758, GHSA-gw9j-5g8h-92qv, UBUNTU-CVE-2026-80758

## What is CVE-2026-80758?

CVE-2026-80758 is an use after free vulnerability in Linux, published on 4 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

futex: Avoid private hash use-after-free on final put

futex_private_hash_put() drops the reference to fph before evaluating
fph->mm for wake_up_var(). futex_ref_put() enables preemption again before
returning. If that put drops the final reference and the task is preempted,
another task can pivot to the replacement hash and free the old hash after
an RCU grace period. The first task then reads fph->mm from the freed
allocation when it resumes.

KASAN reports a slab-use-after-free in futex_private_hash_put(), with the
read at offset 24 in a freed kmalloc-512 allocation. The allocation and
free stacks point to futex_hash_allocate() and the RCU free path,
respectively.

Load the mm pointer while the fph reference is still held and pass the
saved value to wake_up_var(). wake_up_var() uses the pointer as a waitqueue
key and does not dereference the mm through it.

## Which versions are affected by CVE-2026-80758?


## How do I fix CVE-2026-80758?

Apply the vendor's patch.

## Is CVE-2026-80758 being exploited?

There is no known exploitation of CVE-2026-80758 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80758 and fix it if it is affected.

What it is: CVE-2026-80758 is an use after free vulnerability in Linux, published on 4 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-80758 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-2026-80758/ (Markdown: https://insights.sbomify.com/CVE-2026-80758/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80758
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80758
- OSV: https://osv.dev/vulnerability/CVE-2026-80758

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80758/
Summaries are generated and may contain mistakes; the official description above is the record.