Researchers at Citizen Lab warn that athletes attending the Winter Games may be subject to digital surveillance.
A growing number of Western nations and cybersecurity groups have issued digital surveillance warnings for next month's Winter Olympics in Beijing, with some advising foreign athletes to leave personal phones and laptops at home.
Earlier this week, researchers at the University of Toronto's Citizen Lab said a virus-monitoring app all attendees must use was found to have a "simple but devastating" encryption flaw that could allow personal data including health information and voice messages to leak.
"China has a history of undermining encryption technology to perform political censorship and surveillance," researcher Jeffrey Knockel wrote.
"As such, it is reasonable to ask whether the encryption in this app was intentionally sabotaged for surveillance purposes or whether the defect was born of developer negligence."
Citizen Lab said it notified Beijing organisers of the issues in early December, but received no reply.
Canberra-based cybersecurity firm Internet 2.0 also warned in a recent report that official Games software, including a VPN and an anti-virus product, from two of the event's Chinese tech sponsors could potentially collect troves of user data without their knowledge.
'Uncensored does not mean unmonitored'
The Beijing Winter Olympic Organising Committee said that cyber-threat allegations "have zero evidence and concerns are totally unnecessary", adding that "relevant information is only used for the Olympic and Winter Olympic Games".
The International Olympic Committee (IOC) has also dismissed the Citizen Lab claims, citing assessments from two unnamed cybersecurity organisations which "confirmed that there are no critical vulnerabilities".
But such assurances have done little to mollify some Western teams.
National Olympic associations in the United States, Canada, the United Kingdom and Australia have advised athletes to leave their personal devices at home and use temporary burner phones if possible while in China for the Games.
China maintains the world's most sophisticated digital tools to monitor and censor the internet for its citizens, keeping the online world behind a "Great Firewall" and blocking major Western platforms such as Twitter, Facebook and YouTube.
The IOC has said China will give athletes and accredited foreign journalists uncensored internet access through Wi-Fi networks and official SIM cards.
But analysts fear such Wi-Fi networks could still pose potential cybersecurity threats to users, such as surveillance and personal data theft.