"Many of the social networks have suffered from security and privacy problems, although there's no suggestion that they have made the same mistake regarding password security," Cluley added. "As LinkedIn likes to present itself as the professional, business-focused social network, it's particularly disappointing that they didn't have fairly elementary security in place."

LinkedIn is no fledgling social networking startup with little money or experience. After a in May 2011, the company should be able to hire a barrage of security experts, the analysts noted.

This makes the breach harder to understand, Enderle said. "Security problems certainly haven't been uncommon for social networks, but given [LinkedIn's] cash position and the amount of warning, this issue should have been addressed," he said. "It makes the management team appear too inexperienced for a firm of this size... Negligence in a public company typically is a very bad thing because it can force changes at top executive levels."

As for LinkedIn's users, Patrick Moorhead, an analyst with Moor Insights & Strategy, said few will probably leave the site simply because there are few alternatives for a business-oriented social network.

"LinkedIn's reputation is taking hits from industry insiders and techies," he said. "But these kinds of things blow over quickly and won't leave any permanent marks. At least in North America, there isn't a competitor with much scale for users to go to."