---
id: "CVE-2026-93517"
kind: "vulnerability"
aliases: ["CVE-2026-93517"]
title: "X.org X server: GLX heap overflow lets an authenticated client run code"
severity: "high"
cvss: 8.5
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["bsd", "desktop", "infrastructure", "linux", "xorg", "xwayland"]
not_affected_if: ["no-x-server", "patched-version", "wayland-only-no-xwayland"]
published_at: "2026-10-28T14:17:08+00:00"
first_seen_at: "2026-10-28T14:33:23+00:00"
updated_at: "2026-10-28T14:34:21+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93517", "first_seen_at": "2026-10-28T14:33:23+00:00"}]
---

# X.org X server: GLX heap overflow lets an authenticated client run code

A heap buffer overflow in the GLX RenderLarge request handling of the X.org X server and XWayland lets an authenticated X client crash the server or execute code in its context. Affected versions are X.org X server before 21.1.25 and XWayland before 24.1.14.

_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 against `21.1.25`
- Run `Xwayland -version` and compare against `24.1.14`
- Check which package provides the X server with `dpkg -l xserver-xorg-core` or `rpm -q xorg-x11-server-Xorg`

## Fix

- Upgrade X.org X server to `21.1.25` or later
- Upgrade XWayland to `24.1.14` or later
- Apply the distribution's X server security update where a fixed backport is shipped

## Timeline

- 2026-10-28T14:33:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-93517

## From the sources

A heap buffer overflow in handling GLX
RenderLarge request where dataBytes exceeds cmdlen in X.org X server before 21.1.25 and XWayland before 24.1.14 that could be be triggered by an authenticated X client could cause crashes or code execution in X server context.

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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_