# CVE-2026-93519: X.Org X server buffer overflow in XFIXES pointer barriers

Source: https://junglewise.ai/threats/cve-2026-93519-a-buffer-overflow-when-handling-pointer-barriers-in-the-xfixes  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-28. Updated: 2026-10-28  
License: CC BY 4.0 with a link back

CVE-2026-93519 · Severity: high · CVSS 7.8 · Published 2026-10-28

The X.Org X server and XWayland manage display rendering and input handling on Linux systems. A buffer overflow in the XFIXES extension's pointer barrier handling allows authenticated applications to crash the X server or execute arbitrary code with X server privileges. An attacker with local access to run X applications could gain system-level code execution or deny service to all graphical applications.

Technologies: [X.Org X Server](https://junglewise.ai/threats/technologies/x-org-x-server), [X.Org XWayland](https://junglewise.ai/threats/technologies/x-org-xwayland). Vendors: [X.Org](https://junglewise.ai/threats/vendors/x-org).

## Quick answers

**Is CVE-2026-93519 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-93519 being exploited in the wild.

**How severe is CVE-2026-93519?** High severity, with a CVSS score of 7.8, published 28 October 2026.

**Which products and versions are affected?** X.Org X Server before 21.1.25; X.Org XWayland before 24.1.14.

**Is there a fix for CVE-2026-93519?** Yes: fixed in X.Org X server 21.1.25; XWayland 24.1.14. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-93519 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-93519?** Check whether you run X.Org X Server or X.Org XWayland at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in X.Org X server 21.1.25; XWayland 24.1.14

## Technical details

The vulnerability is a stack buffer overflow in input_constrain_cursor() within the Xi module, triggered when handling pointer barrier events. An authenticated X client can create more than 100 pointer barriers, pre-arm them for release, and cause a single pointer motion event to cross all barriers simultaneously, causing the leave event loop to write beyond the 100-entry InputEventList buffer. The fix caps barrier events at 64 and limits barrier creation to 32 per screen.

## Affected products

- X.Org X server before 21.1.25
- X.Org XWayland before 24.1.14

## Timeline

- 2026-10-28: disclosed
- 2026-08-26: patched

## References

- [https://gitlab.freedesktop.org/xorg/xserver/-/commit/1f42cc1f00d9c6d46978ae82dba8a52f4d902369](https://gitlab.freedesktop.org/xorg/xserver/-/commit/1f42cc1f00d9c6d46978ae82dba8a52f4d902369)

## Related threats

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- [X.Org X Server heap buffer overflow in XIPassiveUngrabDevice](https://junglewise.ai/threats/cve-2026-93523-a-heap-buffer-overflow-caused-by-a-xipassiveungrabdevice-request)
- [X.Org X Server heap buffer overflow in CopyArea CPU-to-FBO](https://junglewise.ai/threats/cve-2026-93522-a-heap-buffer-overflow-caused-by-mismatched-size-usage-in)
- [X.Org X Server buffer overflow in RandR ChangeProviderProperty](https://junglewise.ai/threats/cve-2026-93521-a-buffer-overflow-in-randr-changeproviderproperty-requests-in-x)