---
id: "CVE-2026-93523"
kind: "vulnerability"
aliases: ["CVE-2026-93523"]
title: "X.Org X Server: out-of-range modifier in XIPassiveUngrabDevice overflows heap"
severity: "high"
cvss: 7.8
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "linux-desktop", "x.org", "xorg-server", "xwayland"]
not_affected_if: ["no-x-server", "trusted-clients-only"]
published_at: "2026-10-28T17:18:53+00:00"
first_seen_at: "2026-10-28T17:34:10+00:00"
updated_at: "2026-10-28T17:36:16+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93523", "first_seen_at": "2026-10-28T17:34:10+00:00"}]
---

# X.Org X Server: out-of-range modifier in XIPassiveUngrabDevice overflows heap

A malformed XIPassiveUngrabDevice request with an out-of-range modifier value writes past a heap buffer in X.Org X Server and XWayland. An authenticated X client can crash the server or potentially execute code in the X server context.

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

## How to check

- Run `Xorg -version` or `X -version` and compare with `21.1.15`
- Run `Xwayland -version` and compare with `24.1.14`
- Check whether the distribution's xorg-server or xwayland package includes the fix

## Fix

- Update X.Org X Server to `21.1.15` or later
- Update XWayland to `24.1.14` or later
- Apply the distribution's xorg-server and xwayland security updates

## Timeline

- 2026-10-28T17:34:10+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-93523

## From the sources

A heap buffer overflow caused by a XIPassiveUngrabDevice request with an out-of-range modifier value in X.Org X Server before 21.1.15 and XWayland before 24.1.14 could be used by authenticated X clients to crash or potentially execute code in X server context.

---

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