CVE-2026-93834
Qemu-kvm: 9pfs: use-after-free race in tlcreate/twalk allows vm guest escape
What happened?
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.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| qemu-kvmRed Hat | Default status: affected | See vendor advisory |
| qemu-kvmRed Hat | Default status: unaffected | See vendor advisory |
| qemu-kvmRed Hat | Default status: unaffected | See vendor advisory |
| qemu-kvm-maRed Hat | Default status: unaffected | See vendor advisory |
| virt-devel:rhel/qemu-kvmRed Hat | Default status: affected | See vendor advisory |
| virt:rhel/qemu-kvmRed Hat | Default status: affected | See vendor advisory |
| qemu-kvmRed Hat | Default status: affected | See vendor advisory |
| qemu-kvmRed Hat | Default status: unknown | See vendor advisory |
| openshift/ose-rhel-coreos-8Red Hat | Default status: affected | See vendor advisory |
| openshift/ose-rhel-coreos-9Red Hat | Default status: affected | See vendor advisory |
| openshift/ose-rhel-coreos-9Red Hat | Default status: affected | See vendor advisory |
| qemu-kvm-rhevRed Hat | Default status: unaffected | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.