CVE-2025-15559 Unauthenticated OS Command Injection in NesterSoft WorkTime

Critical 9.8 Published 19 Feb 2026 Updated 23 Feb 2026

Unauthenticated attackers can execute arbitrary OS commands with SYSTEM privileges via the guid parameter in the WorkTime server API.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2025-15559?

CVE-2025-15559 is a critical command injection vulnerability in NesterSoft Inc. WorkTime (on-prem/cloud), published on 19 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-78

Which versions are affected by CVE-2025-15559?

It affects 1 product.

Products include Nestersoft Worktime.

How do I fix CVE-2025-15559?

No fix has been published for CVE-2025-15559 yet. Limit exposure of the affected software until one is available.

Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.

Is CVE-2025-15559 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-15559 exists.

Sources

Also known as GHSA-p5gf-vhgm-432f.