Chinese hackers have exploited a zero-day vulnerability in the TrueConf video conferencing software in attacks against government entities in Asia, Check Point reports.
The exploited bug, tracked as CVE-2026-3502 (CVSS score of 7.8), exists because the application does not properly verify updates before applying them.
This results in the execution of malicious code if an attacker could tamper with the update code, and this is the mechanism that was exploited in the observed attack, Check Point says.
TrueConf can be deployed on premises within a private local network, without access to the internet, and is typically used by government, military, and critical infrastructure entities for communication autonomy and privacy.
“By hosting the server on internal hardware, all audio, video, and chat traffic remains strictly contained on-site, with offline activation available for fully air-gapped systems,” Check Point explains.
The TrueConf client’s update flow relies on the connected on-premises server to fetch and install newer versions, but does not perform the necessary integrity and authenticity checks before running the installer.
“TrueConf client update starts when the client detects a version mismatch in favor of the TrueConf on-premises server, the client alerts the user that a newer version is available and offers to download it,” Check Point notes.
As part of the observed attack, which CheckPoint named TrueChaos, the hackers compromised the on-premises TrueConf server, replaced the update package with a malicious one, and then likely sent a link to the target to launch the TrueConf client and trigger the update flow.
“The compromised TrueConf on-premises server was operated by the governmental IT department and served as a video conferencing platform for dozens of government entities across the country, which were all supplied with the same malicious update,” Check Point notes.
Alongside legitimate TrueConf installation components, the modified update package dropped a malicious library and a legitimate executable abused for DLL sideloading to execute the library.
The implant allowed the attackers to perform reconnaissance, prepare for lateral movement, achieve persistence, and fetch additional payloads.
While it did not retrieve the final payload, Check Point observed network communication to an IP used as command-and-control (C&C) infrastructure for Havoc, an open source post-exploitation framework. The cybersecurity firm believes a Chinese threat actor was responsible for the intrusion.
“The exploitation of CVE-2026-3502 did not require the attacker to compromise each endpoint individually. Instead, the attacker abused the trusted relationship between a central on-premises TrueConf server and its clients,” Check Point notes.
TrueConf fixed the zero-day in version 8.5.3 of the client, released in March. On Thursday, the US cybersecurity agency CISA added the bug to its Known Exploited Vulnerabilities (KEV) catalog, urging federal agencies to patch it by April 16.
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