Brother took a personal loan using our joint property as collateral, without my consent?

I am residing in Mumbai, and recently I discovered that my brother has taken a personal loan of ₹10 lakh using the house we jointly own as collateral. He did this without informing or getting my consent. This has put our property at risk, and I feel betrayed. I am not sure how to resolve this or what legal actions I can take against him or the bank. Can I challenge this loan agreement? What steps should I take to protect my share in the property?