Maybe there is no exact Scripture prohibiting cussing as we know it, but surely these Scriptures and more convey the principle of a pure mouth...
Colossians 4:6 (KJV)
Let your speech be alway with grace, seasoned with salt, that ye may know how ye ought to answer every man.
Sure, modern day foul language isn't graceful speech.
Titus 2:7-8 (KJV)
7 In all things shewing thyself a pattern of good works: in doctrine shewing uncorruptness, gravity, sincerity, 8 Sound speech, that cannot be condemned; that he that is of the contrary part may be ashamed, having no evil thing to say of you.
1 Timothy 4:7 (KJV)
7 But refuse profane and old wives' fables, and exercise thyself rather unto godliness.
1 Timothy 6:20 (KJV)
20 O Timothy, keep that which is committed to thy trust, avoiding profane and vain babblings, and oppositions of science falsely so called:
2 Timothy 2:16 (KJV)
16 But shun profane and vain babblings: for they will increase unto more ungodliness.
The word profane means wicked, heathenish...
Philippians 4:8 (KJV)
8 Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report; if there be any virtue, and if there be any praise, think on these things.
I realize that this Scripture says 'think', but truly as a man thinketh in his heart, so is he.
Much of the folly of the Pharisees in Jesus day was b/c they derived their righteousness from obeying the letter of the law to obtain their righteousness.
Much of the folly of today's Pharisees is derived from the fact that if they don't have a specific verse covering a specific item, they ignore the spirit of Scriptures.
Maybe there is no Scripture strictly forbidding modern day 'cursing' per se', but the spirit of the Scriptures dictates that whatever we DO say should be pure, holy, incorruptible, God honoring etc. etc. etc.