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

High 7.8 Published 13 Dec 2023 Updated 23 Jun 2026

Out-of-bounds memory access in Xorg X11 server allows local privilege escalation or remote code execution via X11 forwarding.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2023-6377?

CVE-2023-6377 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 13 Dec 2023. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Weakness: CWE-125

Which versions are affected by CVE-2023-6377?

It affects 5 products.

Linux distribution packages (29)

`tigervnc` Red Hat:rhel_els:6	All versions	`0:1.1.0-25.el6_10.14`
`tigervnc-debuginfo` Red Hat:rhel_els:6	All versions	`0:1.1.0-25.el6_10.14`
`tigervnc-server` Red Hat:rhel_els:6	All versions	`0:1.1.0-25.el6_10.14`
`tigervnc-server-applet` Red Hat:rhel_els:6	All versions	`0:1.1.0-25.el6_10.14`
`tigervnc-server-module` Red Hat:rhel_els:6	All versions	`0:1.1.0-25.el6_10.14`
`xorg-x11-server` SUSE:Enterprise Storage 7.1	All versions	`1.20.3-150200.22.5.85.1`
`xorg-x11-server` SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	All versions	`1.20.3-150200.22.5.85.1`
`xorg-x11-server` SUSE:Linux Enterprise High Performance Computing 15 SP3-ESPOS	All versions	`1.20.3-150200.22.5.85.1`
`xorg-x11-server` SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	All versions	`1.20.3-150200.22.5.85.1`
`xorg-x11-server` SUSE:Linux Enterprise Module for Basesystem 15 SP4	All versions	`1.20.3-150400.38.35.1`
`xorg-x11-server` SUSE:Linux Enterprise Module for Basesystem 15 SP5	All versions	`21.1.4-150500.7.13.1`
`xorg-x11-server` SUSE:Linux Enterprise Module for Development Tools 15 SP4	All versions	`1.20.3-150400.38.35.1`
`xorg-x11-server` SUSE:Linux Enterprise Module for Development Tools 15 SP5	All versions	`21.1.4-150500.7.13.1`
`xorg-x11-server` SUSE:Linux Enterprise Server 12 SP5	All versions	`1.19.6-10.62.1`
`xorg-x11-server` SUSE:Linux Enterprise Server 15 SP2-LTSS	All versions	`1.20.3-150200.22.5.85.1`
`xorg-x11-server` SUSE:Linux Enterprise Server 15 SP3-LTSS	All versions	`1.20.3-150200.22.5.85.1`
`xorg-x11-server` SUSE:Linux Enterprise Server for SAP Applications 12 SP5	All versions	`1.19.6-10.62.1`
`xorg-x11-server` SUSE:Linux Enterprise Server for SAP Applications 15 SP2	All versions	`1.20.3-150200.22.5.85.1`
`xorg-x11-server` SUSE:Linux Enterprise Server for SAP Applications 15 SP3	All versions	`1.20.3-150200.22.5.85.1`
`xorg-x11-server` SUSE:Linux Enterprise Software Development Kit 12 SP5	All versions	`1.19.6-10.62.1`
`xorg-x11-server` SUSE:Linux Enterprise Workstation Extension 15 SP4	All versions	`1.20.3-150200.22.5.85.1`
`xwayland` SUSE:Linux Enterprise Workstation Extension 15 SP4	All versions	`21.1.4-150400.3.26.1`
`xorg-x11-server` SUSE:Linux Enterprise Workstation Extension 15 SP5	All versions	`1.20.3-150200.22.5.85.1`
`xwayland` SUSE:Linux Enterprise Workstation Extension 15 SP5	All versions	`22.1.5-150500.7.11.1`
`xorg-x11-server` openSUSE:Leap 15.4	All versions	`1.20.3-150200.22.5.85.1`
`xorg-x11-server` openSUSE:Leap 15.4	All versions	`1.20.3-150400.38.35.1`
`xwayland` openSUSE:Leap 15.4	All versions	`21.1.4-150400.3.26.1`
`xorg-x11-server` openSUSE:Leap 15.5	All versions	`21.1.4-150500.7.13.1`
`xwayland` openSUSE:Leap 15.5	All versions	`22.1.5-150500.7.11.1`

Products include Debian Debian Linux, Redhat Enterprise Linux Eus, Tigervnc Tigervnc, X.org X Server, X.org Xwayland.

How do I fix CVE-2023-6377?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2023-6377 being exploited?

There is no known exploitation of CVE-2023-6377 in the wild and no public exploit code.

All Debian Debian Linux vulnerabilities

Sources

Also known as AZL-32179, AZL-44700, BELL-CVE-2023-6377, CLSA-2025-1763558418, DEBIAN-CVE-2023-6377, DLA-3686-2 and 10 more.