It depends.

On one hand most commercial NDAs are policy documents. Many people get confused over policy and law. The former is specific to an entity (like a corporation) while the latter applies to society at large.

For example, a company may prohibit you from giving away to someone else a copy of their software that you legally purchased, but that's policy. No law against it.

On the other hand, NDAs are contracts and come under contract law, which makes them a civil legal issue. If you sign and then violate a contract, you may be liable for civil action.

However, you are much better consulting a legal expert than an enthusiast forum.