dbcve.org
WorktimeApplication · Nestersoft

CVE-2025-15559

CRITICAL · 9.8 CVSS v3.1 Published 2026-02-19
Fix available
A fix is available. Upgrade to after 11.8.8 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

NesterSoft WorkTime server contains an OS command injection vulnerability in the API endpoint that handles client download requests. The 'guid' parameter is not properly sanitized before being used in a system call, allowing an unauthenticated attacker to inject arbitrary OS commands. Since the service runs with NT Authority\SYSTEM privileges, exploitation yields complete server compromise.

MitigationImplement strict input validation and sanitization on all API parameters, specifically the 'guid' parameter. Replace any unsafe system calls with parameterized commands or secure APIs that do not execute user-supplied input as shell commands.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
WorktimeApplication
Affected:<= 11.8.8

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm WorkTime server installation
    Look for Nestersoft WorkTime server software on the system. Check installed programs list, or search for WorkTime-related directories and executables.
    Affected if WorkTime server is present on the system
  2. Identify installed version
    Determine the exact version of the installed WorkTime server. Compare the version number to the affected range: version 11.8.8 or lower.
    Affected if Installed version is 11.8.8 or any lower version number
  3. Check if API service is running
    Verify whether the WorkTime server API service is actively running and listening on network ports. Look for processes related to WorkTime and any associated HTTP/HTTPS listeners.
    Affected if The API service is running and accepting connections
  4. Verify client download endpoint accessibility
    Determine if the API endpoint that handles client download requests is exposed and reachable. This endpoint processes the 'guid' parameter.
    Affected if The client download API endpoint is accessible (even locally)
  5. Check service account context
    Inspect the Windows service configuration for WorkTime to confirm it runs under NT Authority\SYSTEM privileges.
    Affected if Service runs with NT Authority\SYSTEM (this indicates potential for full system compromise if exploited)

A system is affected if Nestersoft WorkTime version 11.8.8 or lower is installed, the API service is running, and the client download endpoint is accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 11.8.8
Interim mitigation

Implement strict input validation and sanitization on all API parameters, specifically the 'guid' parameter. Replace any unsafe system calls with parameterized commands or secure APIs that do not execute user-supplied input as shell commands.

Recommended fix Moderate confidence

WorkTime version > 11.8.8 (contact NesterSoft for the exact latest fixed release)

  1. 1. Identify the current NesterSoft WorkTime server version installed
  2. 2. Schedule a maintenance window for the upgrade process
  3. 3. Back up the WorkTime server configuration and database
  4. 4. Download the latest WorkTime server version from the official vendor (NesterSoft)
  5. 5. Stop the WorkTime server services
  6. 6. Install the updated WorkTime server version (version greater than 11.8.8)
  7. 7. Verify the installation completed successfully
  8. 8. Restart WorkTime server services
Caveat Review release notes for any changes to API behavior or required configuration updates after upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Worktime Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA6.0 h
30.0 hours of engineering $5,120
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,192.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-15559 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data