Data on over 6,000 meetings held by Germany's Budeswehr was available online until May 3, according to the German media outlet Die Zeit.
Die Ziet's report came after an audio recording of a conversation between German Air Force officers on the delivery of Taurus long-range missiles to Ukraine and the training of Ukrainian troops was leaked.
The nearly 40-minute conversation was published on March 1 by Margarita Simonyan, the editor-in-chief of Kremlin-controlled TV channel RT.
German Defense Minister Boris Pistorius later said that the call between the officers was held via Webex videoconferencing software hosted on German army servers, but "not all participants adhered to the secure dial-in procedure as required."
Several thousand links containing information about conferences were available online until the evening of May 3, according to Die Zeit. The information reportedly included information on meetings' schedules, agendas, duration, organizers.
The leak could be "severe" as some of the online meetings were secret, Die Zeit said.
Die Ziet journalists could reportedly join the private video conference rooms of some Bundeswehremployees, including the head of the German Air Force, Lieutenant General Ingo Gerhartz. Die Zeit claimed that the meeting had no password protection.
The Budeswehr has reportedly not ruled out the possibility that secret information was leaked as a result.
The Bundeswehr told Die Zeit that it has decided to temporarily stop using Webex.
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