CVE-2025-11234 Qemu-kvm: vnc websocket handshake use-after-free
High 7.5
Published
Updated
Check this codebase for CVE-2025-11234 and fix it if it is affected.
What it is: CVE-2025-11234 is a high-severity use after free vulnerability in Red Hat Enterprise Linux 10, published on 3 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-11234 in the wild and no public exploit code.
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-2025-11234/ (Markdown: https://insights.sbomify.com/CVE-2025-11234/index.md)
A malicious client can cause a denial of service in QEMU's VNC WebSocket handshake via a use-after-free vulnerability before authentication.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-11234?
CVE-2025-11234 is a high-severity use after free vulnerability in Red Hat Enterprise Linux 10, published on 3 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A flaw was found in QEMU. If the QIOChannelWebsock object is freed while it is waiting to complete a handshake, a GSource is leaked. This can lead to the callback firing later on and triggering a use-after-free in the use of the channel. This can be abused by a malicious client with network access to the VNC WebSocket port to cause a denial of service during the WebSocket handshake prior to the VNC client authentication.
Weakness: CWE-416
Which versions are affected by CVE-2025-11234?
Linux distribution packages (40)
qemu-guest-agent AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-img AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-audio-pa AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-block-blkio AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-block-curl AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-block-rbd AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-common AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-core AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-device-display-virtio-gpu AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-device-display-virtio-gpu-ccw AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-device-display-virtio-gpu-pci AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-device-display-virtio-vga AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-device-usb-host AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-device-usb-redirect AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-docs AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-tools AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-ui-egl-headless AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-kvm-ui-opengl AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
qemu-pr-helper AlmaLinux:10 | All versions | 18:10.0.0-14.el10_1.5.alma.1 |
SLOF AlmaLinux:8 | All versions | 20210217-2.module_el8.10.0+3768+dfd76e10 |
hivex AlmaLinux:8 | All versions | 1.3.18-23.module_el8.6.0+2880+7d9e3703 |
hivex AlmaLinux:8 | All versions | 1.3.18-23.module_el8.6.0+3161+a07c0ea5 |
hivex-devel AlmaLinux:8 | All versions | 1.3.18-23.module_el8.6.0+2880+7d9e3703 |
hivex-devel AlmaLinux:8 | All versions | 1.3.18-23.module_el8.6.0+3161+a07c0ea5 |
libguestfs AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-appliance AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-bash-completion AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-devel AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-gfs2 AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-gobject AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-gobject-devel AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-inspect-icons AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-java AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-java-devel AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-javadoc AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-man-pages-ja AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-man-pages-uk AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-rescue AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
libguestfs-rsync AlmaLinux:8 | All versions | 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.alma |
How do I fix CVE-2025-11234?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2025-11234 being exploited?
There is no known exploitation of CVE-2025-11234 in the wild and no public exploit code.
Sources
Also known as ALSA-2026:1831, ALSA-2026:18772, ALSA-2026:5578, AZL-68193, AZL-68202, CLSA-2026-1779580341 and 17 more.