---
id: CVE-2026-93834
title: A use-after-free vulnerability was found in QEMU's 9pfs subsystem
summary: >-
  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 cont…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: Red Hat
product: qemu-kvm
affected:
  - qemu-kvm (all versions)
  - qemu-kvm
  - qemu-kvm
  - qemu-kvm-ma
  - 'virt-devel:rhel/qemu-kvm (all versions)'
  - 'virt:rhel/qemu-kvm (all versions)'
  - qemu-kvm (all versions)
  - qemu-kvm
  - openshift/ose-rhel-coreos-8 (all versions)
  - openshift/ose-rhel-coreos-9 (all versions)
  - qemu-kvm-rhev
published: '2026-09-25'
updated: '2026-09-29'
sourceUpdated: '2026-09-29T21:29:07.663'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93834'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-93834'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2537939'
    label: secalert@redhat.com
  - url: 'https://gitlab.com/qemu-project/qemu/-/work_items/4491'
    label: secalert@redhat.com
  - url: 'https://gitlab.com/qemu-project/qemu/-/work_items/4491'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93834.json
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-93834'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93834'
tags:
  - nvd
  - exploit-available
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00405
epssPercentile: 0.34556
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/suominen/CVE-2026-93834'
  checkedAt: '2026-10-27T19:23:28.798Z'
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-25T13:49:32.754375Z'
ingestedAt: '2026-09-25T14:09:46.369Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux for NVIDIA 26, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux for NVIDIA 26, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-09-25 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93834.json)