A lot of foundations will fail and let water in for one reason or another over time. Just the nature of the beast. It usually does not effect the integrity of the foundation unless the foundation itself failed thus letting in the water. If the foundation failed it would be a red flag. They are $$$ to fix. It could be from various reasons if it is not a failed foundation. What is on the outside of the area ? It could something as simple as regrading the ground to a full french drain install.

I have learned there are 2 kinds of basements: basements that leak now and basements that will leak in the future. My house had your exact problem and it took me 2 years (plus countless research on the web) to figure out the most effective strategy is to keep water away from the house. You may need to regrade your landscaping, possibly install drainage trenches outside, potentially alter patios/sidewalks, and definitely adjust or replace your gutters and downspouts. I also had to get my neighbor to adjust a downspout. I took many of these steps and as a result reduced water intrusion in the corner of my basement from frequent puddles to once or twice a year minor seepage (no standing water - just dampness). Now I am trying to figure out how to address this cove joint. One thing to note - if you are in an area with water table issues, and/or underground water migration (not terribly common but possible) you'll probably have to bit the bullet and put in a french drain and sump pump set up. Hope this helps.