---
id: "CVE-2026-109904"
page: "https://infrastack.ai/live/CVE-2026-109904"
kind: "vulnerability"
aliases: ["CVE-2026-109904"]
title: "X.Org Xwayland: integer overflow lets authenticated clients crash server or leak data"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "xwayland", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["infrastructure", "linux", "x-server", "x.org", "xwayland"]
not_affected_if: ["no-authenticated-x-clients", "patched-version"]
published_at: "2026-11-13T11:17:15+00:00"
first_seen_at: "2026-11-13T11:44:16+00:00"
updated_at: "2026-11-13T11:44:32+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109904", "first_seen_at": "2026-11-13T11:44:16+00:00"}]
exploit_sources: []
---

# X.Org Xwayland: integer overflow lets authenticated clients crash server or leak data

Link for people: https://infrastack.ai/live/CVE-2026-109904 (this .md is for agents)

An integer overflow in the XRes extension's QueryClientIds handler causes a buffer overread in Xwayland before 24.1.15 and X Server before 21.1.26. An attacker with an authenticated X client can crash the server or leak memory contents.

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

## Affected

- vendor:xwayland affected range not listed fixed no fixed version listed

## How to check

- Check the installed Xwayland version with `Xwayland -version` and the X Server version with `Xorg -version`.
- Confirm whether the XRes extension is loaded, which the sources do not say; unknown.

## Fix

- Xwayland: move to `24.1.15` or later.
- X Server: move to `21.1.26` or later.

## Timeline

- 2026-11-13T11:44:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-109904

## From the sources

A buffer overread caused by an integer-overflow in Proc/SProcXResQueryClientIds in X.Org xwayland before 24.1.15 and X Server before 21.1.26 could be used by attackers on authenticated X clients to crash the server or leak out information.

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