Two U.S. senators asked Facebook Inc. on Tuesday about a possible security flaw in its messenger application designed for children that would allow adults to contact underage users without parental approval.

In a letter to the Menlo Park, California-based company’s chief executive officer Mark Zuckerberg, Sen. Ed Markey, D-Massachusetts, and Sen. Richard Blumenthal, D-Connecticut, pushed for “more transparency” around the alleged flaw in Facebook Messenger Kids’ app.

Sen. Ed Markey (D-MA). March 14, 2007. Photo: Diego M. Radzinschi/NLJ