Samsung's flagship smartphone, the Galaxy S4, has a security flaw that could let malicious software track emails and record data communications, experts say.

Researchers at Ben-Gurion University's Cyber Security Labs say the S4's Knox security platform -- which Samsung has been pitching to agencies like the U.S. Department of Defense as making the S4 safe for secure communications -- contains a vulnerability that allegedly could expose secure data to hackers, CNET reported Tuesday.

Samsung, for its part, has told the Wall Street Journal it's looking into the issues and doesn't believe the problem is as serious as the researchers have said in announcing their findings.

While the Israeli researchers acknowledge the Knox platform is the most advanced security-focused infrastructure for mobile phones, the vulnerability presents a risk that should not be ignored, they said.

"Knox has been widely adopted by many organizations and government agencies and this weakness has to be addressed immediately before it falls into the wrong hands," doctoral student Mordechai Guri, who discovered the flaw, said. "We are also contacting Samsung in order to provide them with the full technical details of the breach so it can be fixed immediately."