CVE-2023-6377

What it actually does

Out-of-bounds memory reads and writes triggered when querying or modifying XKB button actions during input device transitions such as touchpad to mouse in xorg-server.

Why it matters to the business

Local users on systems running affected Xorg releases may obtain elevated privileges, enabling unauthorized access to files, processes, or network resources; X11 forwarding scenarios increase exposure to remote code execution.

How an attack unfolds

An attacker with a local session or X11 forwarding capability crafts input sequences that cause the X server to query or alter XKB button actions, resulting in out-of-bounds memory access that can be leveraged for privilege escalation or code execution.

How to fix it

Update xorg-server to the commit 0c1a93d319558fe3ab2d94f51d174b4f93810afd or later; rebuild and redeploy packages containing the patched server binary.

How to confirm the fix worked

Verify the installed xorg-server binary or source tree contains commit 0c1a93d319558fe3ab2d94f51d174b4f93810afd; test input device transitions under XKB to confirm absence of crashes or memory errors.

Typical attack path

1. Obtain local shell or establish X11 forwarding session
2. Load or switch input devices to trigger XKB button action changes
3. Induce out-of-bounds read/write via crafted XKB requests
4. Use resulting memory corruption to escalate privileges or execute code

How to detect it

Inspect X server logs for segmentation faults or memory errors during input device or XKB events; correlate with unusual privilege changes or new processes spawned from X clients.

What your security team should do

• Prioritize patching xorg-server on multi-user or remotely accessible systems
• Disable X11 forwarding where not required
• Review and restrict local X server access via policy or sandboxing
• Monitor upstream distributions for updated packages