CVE-2025-15559
Critical
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.
SeverityCritical
CVSS9.8
Exploit probability—
ProductNestersoft Worktime
PublishedFeb 19, 2026
First seenFeb 19, 2026
Weakness typeCWE-78OS command injection
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| nestersoft worktime | v ≤ 11.8.8 | — |
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