---
id: CVE-2026-105959
title: >-
  Spice-server: spice: heap buffer overflow via glz dictionary max_encoders
  integer truncation
summary: >-
  A flaw was found in spice-server. The GLZ encoder dictionary restore path
  truncates a size_t allocation size to int when calling the malloc callback,
  allowing a malicious authenticated SPICE client during VM live migration to
  trigger a m…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-190
vendor: Red Hat
product: spice-server
affected:
  - spice-server (all versions)
  - spice (all versions)
  - spice (all versions)
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T14:04:30.322816Z'
published: '2026-10-16'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T14:04:46.377Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-105959'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-105959'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2554008'
    label: RHBZ#2554008
  - url: 'https://gitlab.freedesktop.org/spice/spice/-/merge_requests/253'
tags:
  - cve.org
ingestedAt: '2026-10-16T12:05:46.478Z'
---

## Overview

A flaw was found in spice-server. The GLZ encoder dictionary restore path truncates a size_t allocation size to int when calling the malloc callback, allowing a malicious authenticated SPICE client during VM live migration to trigger a massive heap buffer overflow by sending a crafted max_encoders value in migration data.

## Affected

- `spice-server (all versions)`
- `spice (all versions)`
- `spice (all versions)`

## Remediation

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

### Workarounds

This vulnerability is only exploitable during VM live migration by an authenticated SPICE client. If live migration is not required, disabling it eliminates the attack surface. If live migration is needed, restrict SPICE client connections to trusted networks using firewall rules and enforce strong authentication (TLS with mutual certificate validation, or SASL with strong credentials) to limit who can connect as a SPICE client.