In the wake of news reports about previously undisclosed security vulnerabilities at the flagging social network Google+, Alphabet Inc. and Google Inc. were hit Monday with a lawsuit claiming that Google+ allowed third-party application developers access to users' private profile data between 2015 and March 2018.

“While this information was supposed to be protected, and shared only with expressed permissions and limitations, defendants allowed third-party application developers to improperly collect the personal information of up to 500,000 Google+ users,” wrote lawyers representing two plaintiffs, Google+ account holders from California and Florida.

On Monday, the Wall Street Journal reported that the Mountain View, California-based company exposed data—full names, photos, contact information and occupation—of thousands of users of Google+. Google said it chose not to disclose the breach when it was discovered in March because the company found no evidence of data misuse. Alphabet announced Monday it plans to permanently shut down the consumer functionality of Google+.

The lawsuit was filed in the Northern District of California by lawyers at Morgan & Morgan and Arnold Law Firm. This is the second time in less than a month that same law firm tandem has taken aim at an internet giant with breach claims in Northern California courts. The firms sued Facebook Inc. in the same venue shortly after the social networking giant announced late last month that it had discovered a security breach affecting almost 50 million accounts.

“Given that Google+ was launched to challenge Facebook, the recent data security incidents suffered by Facebook users should have made defendants more sensitive to the necessary protection of Google+ users' data,” the lawyers wrote in Monday's complaint. “Instead, defendants allowed this vulnerability in its system to endure for nearly three years, all the while leaking private information to unauthorized third parties.”

Morgan & Morgan's John Yanchunis, who is based in Tampa, Florida, was traveling Tuesday and unavailable for comment. Yanchunis is also lead counsel in separate multidistrict litigation targeting Yahoo Inc. with claims stemming from a string of data breaches affecting billions of accounts. Yanchunis and defense counsel in the Yahoo case announced in court papers last month that they had reached an ”agreement in principle” to settlement terms in that case.

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