Qemu-kvm: 9pfs: use-after-free race in tlcreate/twalk allows vm guest escape (CVE-2026-93834) | HOL Guard CVE

High · CVSS 8.8CVE-2026-93834

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

Answer in brief

CVE-2026-93834 records a High severity (CVSS 8.8) vulnerability in Qemu-kvm: 9pfs: use-after-free race in tlcreate/twalk allows vm guest escape. The current sources do not mark it as known exploited. The current feed maps Red Hat/openshift/ose-rhel-coreos-8 (generic), Red Hat/openshift/ose-rhel-coreos-9 (generic), Red Hat/qemu-kvm (generic), Red Hat/virt-devel:rhel/qemu-kvm (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.8
Exploitation: Not marked as known exploited
Affected software: 5 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 8.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Red Hat/openshift/ose-rhel-coreos-8 (generic), Red Hat/openshift/ose-rhel-coreos-9 (generic), Red Hat/qemu-kvm (generic), Red Hat/virt-devel:rhel/qemu-kvm (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Red Hat/openshift/ose-rhel-coreos-8generic	*	Not reported
Red Hat/openshift/ose-rhel-coreos-9generic	*	Not reported
Red Hat/qemu-kvmgeneric	*	Not reported
Red Hat/virt-devel:rhel/qemu-kvmgeneric	*	Not reported
Red Hat/virt:rhel/qemu-kvmgeneric	*	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Red Hat/openshift/ose-rhel-coreos-8, Red Hat/openshift/ose-rhel-coreos-9, Red Hat/qemu-kvm.
Review the reported fix. Source-reported workaround: Do not configure 9pfs/VirtFS filesystem sharing (-fsdev, -virtfs) on affected QEMU instances. If host-guest file sharing is required, use virtio-fs (virtiofsd) as an alternative, which does not use the vulnerable 9pfs code path.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.