Unauthenticated OS Command Injection in NesterSoft WorkTime
An unauthenticated attacker can inject OS commands when calling a server API endpoint in NesterSoft WorkTime. The server API call to generate and download the WorkTime client from the WorkTime server is vulnerable in the “guid” parameter. This allows an attacker to execute arbitrary commands on the WorkTime server as NT Authority\SYSTEM with the highest privileges. Attackers are able to access or manipulate sensitive data and take over the whole server.
The vendor did not respond to our communication attempts anymore. It is currently as of February 2026 unclear, whether a patch is available. Please contact the vendor to request a patch for the identified critical security issues.
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Tobias Niemann, SEC Consult Vulnerability Lab
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Daniel Hirschberger, SEC Consult Vulnerability Lab