# CVE-2026-33150: Use After Free in libfuse

> A local attacker can trigger a use-after-free in libfuse's io_uring subsystem to crash processes or execute arbitrary code, particularly in containerized environments.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 20 Mar 2026
- **Updated:** 15 Jul 2026
- **Also known as:** BELL-CVE-2026-33150, DEBIAN-CVE-2026-33150, GHSA-qxv7-xrc2-qmfx

## What is CVE-2026-33150?

CVE-2026-33150 is a high-severity use after free vulnerability in libfuse, published on 20 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

libfuse is the reference implementation of the Linux FUSE. From version 3.18.0 to before version 3.18.2, a use-after-free vulnerability in the io_uring subsystem of libfuse allows a local attacker to crash FUSE filesystem processes and potentially execute arbitrary code. When io_uring thread creation fails due to resource exhaustion (e.g., cgroup pids.max), fuse_uring_start() frees the ring pool structure but stores the dangling pointer in the session state, leading to a use-after-free when the session shuts down. The trigger is reliable in containerized environments where cgroup pids.max limits naturally constrain thread creation. This issue has been patched in version 3.18.2.

Weakness: CWE-825 (Expired Pointer Dereference), CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-33150?

It affects 1 product.


Products: Libfuse Project Libfuse.

## How do I fix CVE-2026-33150?

Upgrade to a fixed version.

## Is CVE-2026-33150 being exploited?

There is no known exploitation of CVE-2026-33150 in the wild and no public exploit code.

Public exploit code:

- RingWraith: CVE-2026-33150 and CVE-2026-33179 — Use-After-Free and NULL Dereference in libfuse io_uring (github_poc): https://github.com/abhinavagarwal07/abhinavagarwal07.github.io

## Other vulnerabilities in libfuse

- [CVE-2010-3879](https://insights.sbomify.com/CVE-2010-3879/): Path traversal in n/a (medium 5.8)
- [CVE-2026-33179](https://insights.sbomify.com/CVE-2026-33179/): libfuse: NULL Pointer Dereference and Memory Leak in io_uring Queue Initialization (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33150 and fix it if it is affected.

What it is: CVE-2026-33150 is a high-severity use after free vulnerability in libfuse, published on 20 Mar 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-2026-33150 in the wild and no public exploit code.

Affected product: libfuse. 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-2026-33150/ (Markdown: https://insights.sbomify.com/CVE-2026-33150/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33150
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33150
- OSV: https://osv.dev/vulnerability/CVE-2026-33150

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33150/
Summaries are generated and may contain mistakes; the official description above is the record.