Conn. Gen. Stat. § 21 § 21-83

(a) An owner and a resident may include in a rental agreement terms and conditions not prohibited by law, including rent, term of the agreement and other provisions governing the rights and obligations of the parties. No rental agreement shall contain the following:

(1) Any provision by which the resident agrees to waive or forfeit rights or remedies under this chapter and sections 47a-21, 47a-23 to 47a-23b, inclusive, 47a-26 to 47a-26h, inclusive, 47a-35 to 47a-35b, inclusive, 47a-41a, 47a-43 and 47a-46, or under any section of the general statutes or any municipal ordinance, unless such section or ordinance expressly states that such rights may be waived;

(2) Any provision which permits the owner to terminate the rental agreement for failure to pay rent unless such rent is unpaid when due and the resident fails to pay rent within (A) nine days thereafter, or (B) fourteen days thereafter if an online rental payment system prevented the payment of rent when due;

(3) Any provision which permits the owner to collect a penalty fee for late payment of rent without allowing the resident a minimum of nine days beyond the due date in which to remit or which provides for the payment of rent in a reduced amount if such rent is paid prior to the expiration of such grace period;

(4) Any provision which permits the owner to charge a penalty for late payment of rent in excess of five per cent of the total rent due for the mobile manufactured home space or lot or four per cent of the total rent due for the mobile manufactured home and mobile manufactured home space or lot;

(5) Any provision which allows the owner to increase the total rent or change the payment arrangements during the term of the rental agreement;

(6) Any provision allowing the owner to charge an amount in excess of one month's rent for a security deposit or to retain the security deposit upon termination of the rental agreement if the resident has paid his rent in full as of the date of termination and has caused no damage to the property of the owner or to waive the resident's right to the interest on the security deposit pursuant to section 47a-21;

(7) Any provision allowing the owner to charge an entrance fee to a resident assuming occupancy;

(8) Any provision authorizing the owner to confess judgment on a claim arising out of the rental agreement;

(9) Any provision which waives any cause of action against or indemnification from an owner, by a resident for any injury or harm caused to such resident, his family or his guests, or to his property, or the property of his family or his guests resulting from any negligence of the owner, his agents or his assigns in the maintenance of the premises or which otherwise agrees to the exculpation or limitation of any liability of the owner arising under law or to indemnify the owner for that liability or the costs connected therewith;

(10) Any provision permitting the owner to dispossess the resident without resort to court order;

(11) Any provision consenting to the distraint of the resident's property for rent;

(12) Any provision agreeing to pay the owner's attorney's fees in excess of fifteen per cent of any judgment against the resident in any action in which money damages are awarded;

(13) Any provision which denies to the resident the right to treat as a breach of the agreement, a continuing violation by the owner, substantial in nature, of any provision set forth in the rental agreement or of any state statute unless the owner discontinues such violation within a reasonable time after written notice is given by the resident by registered or certified mail.

(b) A provision prohibited by this chapter included in a rental agreement is unenforceable.