---
title: "CVE-2026-93517: X.org X server - Buffer Overflow"
description: "X.org X server < 21.1.25 and XWayland < 24.1.14 contain a heap buffer overflow caused by improper handling of GLX RenderLarge request where dataBytes exceeds cmdlen, letting authenticated X clients cause crashes or execute code."
url: https://panop.io/threat-heartbeat/CVE-2026-93517/
---

# CVE-2026-93517 X.org X server - Buffer Overflow

X.org X server < 21.1.25 and XWayland < 24.1.14 contain a heap buffer overflow caused by improper handling of GLX RenderLarge request where dataBytes exceeds cmdlen, letting authenticated X clients cause crashes or execute code.

CVSS base score 8.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-93517)

## Details

Type

Buffer Overflow

Impact

Remote Code Execution, Denial Of Service

CVSS vector

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Published

28 October 2026

Updated

29 October 2026

Weakness

[CWE-122](https://cwe.mitre.org/data/definitions/122.html)

## Vendor fix

Update to X.org X server 21.1.25, XWayland 24.1.14 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-93517](https://nvd.nist.gov/vuln/detail/CVE-2026-93517)
- [https://gitlab.freedesktop.org/xorg/xserver/-/commit/2abe4632d793314d3d5f28c19583fb76019f5ce4](https://gitlab.freedesktop.org/xorg/xserver/-/commit/2abe4632d793314d3d5f28c19583fb76019f5ce4)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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