The answer to 'shut-off valve overflowing' is that the shut-off valve, which is used to turn off the water supply to a specific fixture or area of the home, is likely malfunctioning and allowing water to continue flowing even when it's in the 'off' position. This can be caused by a variety of issues, such as a broken valve, debris buildup, or a problem with the valve's internal components.
If your shut-off valve is overflowing, the first step is to try turning the valve clockwise to fully close it. If that doesn't stop the water flow, you may need to shut off the main water supply to the home to prevent further flooding. Once the water is turned off, you can inspect the valve for any obvious issues, such as cracks or debris. If you're comfortable doing so, you can try to disassemble and clean the valve, or replace it entirely. However, if the problem persists or you're not confident in your ability to fix it, it's best to call a professional plumber to diagnose and repair the issue.