A critical security flaw in mobile networks allowed attackers to access sensitive device information during phone calls, raising alarm over potential exploitation by foreign intelligence services.

A major vulnerability in mobile networks has been discovered, enabling callers to obtain sensitive information about the devices they are contacting. The flaw, active during the initial connection phase of a call, could reveal the smartphone’s unique 15-digit IMEI number as well as details about its model and operating system version—even before the recipient answers. Security experts warn that such data could be exploited to facilitate targeted cyberattacks, including the deployment of spyware.

Germany’s Federal Office for the Protection of the Constitution has classified the issue as a significant security risk. Officials believe foreign intelligence agencies and cybercriminals could leverage the leaked data to conduct espionage or other malicious activities. Concerns became acute when a politician and member of the Foreign Affairs Committee, Roderich Kiesewetter, had his device information extracted during a test call. He described the vulnerability as a major security breach with potentially serious ramifications for public officials and private citizens alike.

Telecom providers impacted by the flaw have responded by updating their systems to close the loophole. Companies like Deutsche Telekom, Vodafone, and Telefónica admit the issue, which violates global telecom standards, existed under specific conditions and claim adjustments have been implemented to limit data exposure during calls. However, questions remain over how long the flaw was active, why it was not identified earlier, and whether similar vulnerabilities persist in international networks. Experts are now calling for stricter oversight of mobile network protocols to prevent such incidents in the future.