---
id: "CVE-2026-105959"
kind: "vulnerability"
aliases: ["CVE-2026-105959"]
title: "spice-server: integer truncation in GLZ restore enables heap overflow during migration"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "other"
products: [{"name": "spice-server", "fixed": [], "affected": "all versions (no fixed version published)", "ecosystem": "vendor"}]
ecosystems: []
tags: ["auth-required", "kvm", "live-migration", "other", "qemu", "spice-server", "virtualization"]
not_affected_if: ["no-live-migration", "no-spice-display"]
published_at: "2026-10-16T12:16:31+00:00"
first_seen_at: "2026-10-23T21:57:12+00:00"
updated_at: "2026-10-25T03:47:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-105959", "first_seen_at": "2026-10-23T21:57:12+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-25T03:47:50+00:00"}]
---

# spice-server: integer truncation in GLZ restore enables heap overflow during migration

spice-server truncates a size_t allocation size to int in the GLZ encoder dictionary restore path, so a crafted max_encoders value in VM live migration data can cause a large heap buffer overflow. An attacker with an authenticated SPICE client connection during live migration could corrupt heap memory on the host.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:spice-server affected all versions (no fixed version published) fixed ?

## How to check

Run 'spice-server' package check (rpm -q spice-server or dpkg -l libspice-server1). Any version is currently treated as affected. Then check whether guests use SPICE graphics (virsh dumpxml <vm> | grep -i "graphics type='spice'" or a -spice option on the qemu command line) and whether live migration is used. You are exposed only if both are true.

## Fix

No fixed spice-server release as of 2026-10-25 (Debian: unfixed; Tenable: no vendor patch). Watch Debian bug 1151202 and the Red Hat CVE page. Until then, reduce exposure as described under mitigation.

## Timeline

- 2026-10-23T21:57:12+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-105959
- 2026-10-25T03:47:50+00:00 analyst — Red Hat CVE page and Debian tracker (Debian bug 1151202) read: no upstream fix or fixed version as of 2026-10-25; Debian lists 0.15.1, 0.15.2 and 0.16.0 as vulnerable and unfixed; CVE record says all versions affected. No PoC or exploitation found. Red Hat's mitigation text is labelled AI-generated, so I did not mark anything verified.

## Documents

- [advisory] Red Hat CVE-2026-105959 https://access.redhat.com/security/cve/cve-2026-105959
- [mentions] Debian tracker CVE-2026-105959 https://security-tracker.debian.org/tracker/CVE-2026-105959

## From the sources

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.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_