---
id: CVE-2023-3255
title: 'Qemu: vnc: infinite loop in inflate_buffer() leads to denial of service'
summary: >-
  A flaw was found in the QEMU built-in VNC server while processing
  ClientCutText messages. A wrong exit condition may lead to an infinite loop
  when inflating an attacker controlled zlib buffer in the `inflate_buffer`
  function. This could …
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-835
vendor: Red Hat
product: 'virt-devel:rhel'
affected:
  - 'virt-devel:rhel (all versions)'
  - 'virt:rhel (all versions)'
  - qemu-kvm (all versions)
  - qemu-kvm
  - qemu-kvm
  - qemu-kvm-ma
  - 'virt:av/qemu-kvm'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2025-10-17T17:14:24.314787Z'
published: '2023-09-13'
updated: '2026-11-01'
sourceUpdated: '2026-11-01T03:01:56.984Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2023-3255'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2024:2135'
    label: 'RHSA-2024:2135'
  - url: 'https://access.redhat.com/errata/RHSA-2024:2962'
    label: 'RHSA-2024:2962'
  - url: 'https://access.redhat.com/security/cve/CVE-2023-3255'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2218486'
    label: RHBZ#2218486
tags:
  - cve.org
epss: 0.01891
epssPercentile: 0.7963
ingestedAt: '2026-11-05T18:28:50.675Z'
---

## Overview

A flaw was found in the QEMU built-in VNC server while processing ClientCutText messages. A wrong exit condition may lead to an infinite loop when inflating an attacker controlled zlib buffer in the `inflate_buffer` function. This could allow a remote authenticated client who is able to send a clipboard to the VNC server to trigger a denial of service.

## Affected

- `virt-devel:rhel (all versions)`
- `virt:rhel (all versions)`
- `qemu-kvm (all versions)`
- `qemu-kvm`
- `qemu-kvm`
- `qemu-kvm-ma`
- `virt:av/qemu-kvm`

## Remediation

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