3CX before 18 Update 2 Security Hotfix build 18.0.2.315 on Windows allows unauthenticated remote attackers to read certain files via /Electron/download directory traversal. Files may have credentials, full backups, call recordings, and chat logs.

An issue was discovered in the 3CX Phone System Management Console prior to version 18 Update 3 FINAL. An unauthenticated attacker could abuse improperly secured access to arbitrary files on the server (via /Electron/download directory traversal in conjunction with a path component that uses backslash characters), leading to cleartext credential disclosure. Afterwards, the authenticated attacker is able to upload a file that overwrites a 3CX service binary, leading to Remote Code Execution as NT AUTHORITY\SYSTEM on Windows installations. NOTE: this issue exists because of an incomplete fix for CVE-2022-48482.