Sudden unwanted interruption in your daily routine.
You may be feeling frustrated for being stuck at some point in your life.
Dreaming that cobras or vipers bite your leg indicates worries and insecurities regarding your ability to achieve your interests or goals. You may feel frustrated and annoyed because you have noticed recently an unexpected obstacle blocking your way on one aspect of your life.
Dreaming about snakes or vipers biting your legs might be expressing your disappointment at seeing that your plans are not being fulfilled or reached, maybe something is happening outside of your plans.
Consider the snake as representing something negative and dangerous in your wake life that comes from nowhere (usually the way snakes attack in real life) to alter your daily routine.
This dream can just be projecting your anxiety for an abrupt halt when reaching your goals or in a key activity in your life which is suddenly imposed on you.