Hackers exploit TrueConf zero-day to push malicious software updates

Hackers have targeted TrueConf conference servers in attacks that exploit a zero-day vulnerability, allowing them to execute arbitrary files on all connected endpoints. The flaw is tracked as CVE-2026-3502 and received a medium severity score. It stems from a missing integrity check in the software’s update mechanism, which can be used to replace the legitimate update with a malicious variant. TrueConf is a video conferencing platform that can run as a self-hosted server. Although it also supports cloud deployments, it is generally designed for closed, offline environments. According to the vendor, more than 100,000 organizations transitioned to TrueConf during the COVID-19 pandemic for remote online business activities. Among TrueConf users are military forces, government agencies, oil and gas corporations, and air traffic management companies. CheckPoint researchers have been tracking a campaign they track as TrueChaos that, since the beginning of the year, has exploited CVE-2026-3502 in zero-day attacks targeting government entities in Southeast Asia. “An attacker who gains control of the on-premises TrueConf server can replace the expected update package with an arbitrary executable, presented as the current application version, and distribute it to all connected clients,” CheckPoint says. “Because the client trusts the server-provided update without proper validation, the malicious file can be delivered and executed under the guise of a legitimate TrueConf update.” The ...