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Fencer Vulns
high 8.8

CVE-2026-93834 json

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

published 2026-09-25 45 d ago modified 2026-11-05 4 d ago also EUVD-2026-87092

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

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 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.

Patch / fix

  • qemu Debian 14 1:11.1.2+ds-1

debian advisories DEBIAN-CVE-2026-93834

  • qemu SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 10.0.13-160000.2.1
  • qemu-linux-user SLES for SAP applications 16.0, SLES 16.0 10.0.13-160000.2.1

suse advisories SUSE-SU-2026:24115-1SUSE-SU-2026:24159-1

  • qemu openSUSE Leap 16.0 10.0.13-160000.2.1
  • qemu-linux-user openSUSE Leap 16.0 10.0.13-160000.2.1
  • qemu openSUSE Tumbleweed 11.1.1-2.1

opensuse advisories openSUSE-SU-2026:22047-1openSUSE-SU-2026:12049-1

  • qemu Azure Linux 3.0 10.1.0-2

azure linux advisories AZL-105278

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-93834 updated cvss 8.8

qemu-kvm: 9pfs: use-after-free race in Tlcreate/Twalk allows VM guest escape

  • Red Hat Enterprise Linux 8 qemu-img, qemu-kvm, qemu-kvm-core, qemu-kvm-tests, qemu-kvm-common, qemu-guest-agent, +8 more Red Hat Enterprise Linux 9 qemu-img, qemu-kvm, qemu-kvm-core, qemu-kvm-tools, qemu-pr-helper, qemu-kvm-common, +16 more Red Hat Enterprise Linux 10 qemu-kvm
    affected: workaround, no fix available
  • Red Hat Enterprise Linux for NVIDIA 26 qemu-kvm
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available
  • Red Hat Enterprise Linux 6 qemu-img, qemu-kvm, qemu-kvm-tools, qemu-guest-agent, qemu-guest-agent-win32 Red Hat Enterprise Linux 7 qemu-img, qemu-kvm, libcacard, qemu-img-ma, qemu-kvm-ma, qemu-kvm-tools, +5 more Red Hat OpenStack Platform 13 (Queens) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
45 d ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • gitlab.com https://gitlab.com/qemu-project/qemu/-/work_items/4491 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux for NVIDIA 26
  • Red Hat Red Hat OpenShift Container Platform 4
  • Red Hat Red Hat OpenShift Container Platform 5
  • Red Hat Red Hat OpenStack Platform 13 (Queens)

Classification

Weakness

References

Sources

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