USART RX interrupt racing condition

I am designing an RS-485 interface with STM32F0xx series MCU.

The scheme uses USART RX interrupt.

I am wondering, if I set up the baud rate as certain value(for example, 9600), is there possibility that the interrupt fire more often than every one character time due to noise or some other disturbance in the RS-485 interface?

I am worried that if above happen, it might lock up the MCU and prevent it from doing other tasks.