# CVE-2026-93834: Qemu-kvm: 9pfs: use-after-free race in tlcreate/twalk allows vm guest escape

> A race condition in QEMU's 9pfs allows guest users to trigger a use-after-free, leading to VM escape and arbitrary host code execution.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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:** 25 Sep 2026
- **Updated:** 25 Sep 2026
- **Also known as:** AZL-105278, DEBIAN-CVE-2026-93834, ECHO-cb4a-4db7-9170, GHSA-86c2-8qp8-q2vh, OESA-2026-4584, OESA-2026-4585, OESA-2026-4586, OESA-2026-4587, UBUNTU-CVE-2026-93834

## What is CVE-2026-93834?

CVE-2026-93834 is a high-severity use after free vulnerability in Red Hat Enterprise Linux 10, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution (VM escape) as the QEMU process user.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-93834?


## How do I fix CVE-2026-93834?

Apply the vendor's patch.

## Is CVE-2026-93834 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-93834 exists.

Public exploit code:

- Tracking the QEMU CVE-2026-93834 9pfs fid-path use-after-free guest-to-host escape (github_poc): https://github.com/suominen/CVE-2026-93834

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93834 and fix it if it is affected.

What it is: CVE-2026-93834 is a high-severity use after free vulnerability in Red Hat Enterprise Linux 10, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-93834 exists.

Affected product: Red Hat Enterprise Linux 10. 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-2026-93834/ (Markdown: https://insights.sbomify.com/CVE-2026-93834/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93834
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93834
- OSV: https://osv.dev/vulnerability/CVE-2026-93834

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93834/
Summaries are generated and may contain mistakes; the official description above is the record.