Description

A remote unauthorized attacker with network access via port 4307/TCP to the TrueConf server versions 5.3.X to 5.3.9, 5.4.X to 5.4.9, 5.5.X to 5.5.5, and earlier could use a specially crafted script to break out of the isolated environment and execute arbitrary code on the host system.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.0",
  "pubDate": "2026-08-19T17:21:01.130Z",
  "pubdate": "2026-08-19T17:21:01.130Z",
  "executiveSummary": "A remote code execution vulnerability exists in the TrueConf server affecting multiple version branches. Specifically, versions 5.3.X to 5.3.9, 5.4.X to 5.4.9, 5.5.X to 5.5.5, and earlier iterations are susceptible to sandbox breakout exploitations. The vulnerability enables a remote, unauthorized threat actor with network access to target the application and execute arbitrary system commands on the underlying host operating system. The flaw stems from insufficient isolation and inadequate boundary enforcement within the processing environment handled by the service listening on port 4307/TCP. Successful exploitation grants the adversary the capability to compromise the integrity, confidentiality, and availability of the host infrastructure. The risk implications are severe, as unauthorized remote access combined with arbitrary code execution can lead to total system takeover, lateral movement within the network, and deployment of secondary payloads. Exploitation requires network connectivity to the specified listening port and the execution of a specially crafted script designed to manipulate the isolation layer.",
  "technicalDetails": "The vulnerability resides in the TrueConf server environment handling processes exposed via TCP port 4307. The root cause involves a failure in the security sandbox mechanism, allowing input passed to the service to bypass confinement boundaries. Affected software includes TrueConf server versions 5.3.X through 5.3.9, 5.4.X through 5.4.9, 5.5.X through 5.5.5, and all preceding versions lacking the appropriate isolation patches.\nExploitation does not require prior authentication or elevated privileges, making it accessible to any remote unauthorized attacker with direct network reachability to the target port. The attack vector involves sending a specially crafted script or payload through port 4307/TCP. Upon receipt, the vulnerable component parses and processes the input without adequate sanitization or strict sandbox restrictions.\nThe attack flow proceeds as follows: First, the remote adversary establishes a network connection to port 4307/TCP on the targeted TrueConf server. Second, the attacker transmits the malicious, custom-tailored script designed to exploit logic flaws in the isolation boundary. Third, the processing engine improperly interprets the instructions, permitting the payload to break out of the intended constrained virtualized or restricted execution context. Finally, the payload executes arbitrary system commands directly on the host operating system under the security context of the service process, resulting in complete host compromise and post-exploitation capabilities such as persistence, data exfiltration, or internal reconnaissance."
}