---
id: "CVE-2026-109090"
kind: "vulnerability"
aliases: ["CVE-2026-109090"]
title: "libXi: malicious X server causes heap overflow via DEVICE_ENABLE reply"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "libxi", "linux", "x11"]
not_affected_if: ["no-x11-clients", "wayland-only"]
published_at: "2026-10-27T17:16:57+00:00"
first_seen_at: "2026-10-27T17:32:45+00:00"
updated_at: "2026-10-27T17:34:38+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109090", "first_seen_at": "2026-10-27T17:32:45+00:00"}]
---

# libXi: malicious X server causes heap overflow via DEVICE_ENABLE reply

libXi, the X Input extension client library, can overflow a heap buffer when it processes a DEVICE_ENABLE reply from an X server. A malicious X server can send an oversized reply to trigger the overflow, which may let it run code in the client application.

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

## How to check

- `pkg-config --modversion xi` to see the installed libXi version
- Check whether your distribution package for libXi is older than the fixed release

## Fix

- Upgrade libXi to `1.8.4` or later through your OS package manager

## Timeline

- 2026-10-27T17:32:45+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-109090

## From the sources

A malicious X server could cause a heap overflow by injecting a large DEVICE_ENABLE reply when processed by libXi before 1.8.4.

---

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