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VulnerabilityPublished Updated

CVE-2025-15559: NesterSoft WorkTime (on-prem/cloud) · OS Command Injection

Affects NesterSoft WorkTime (on-prem/cloud)Source CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
NesterSoft Inc.WorkTime (on-prem/cloud)Affected
  • <=11.8.8
Fixed in–

AI-suggested

  1. Immediately restrict network access to the vulnerable API endpoint by implementing firewall rules or network segmentation to limit exposure only to trusted internal IPs or VPN users.
  2. Monitor and log all requests to the API endpoint, especially those containing unusual or suspicious 'guid' parameter values, to detect potential exploitation attempts.
  3. Apply strict input validation and sanitization on the 'guid' parameter at the application layer if possible, using allowlists or escaping special characters to prevent command injection.
  4. Deploy Web Application Firewalls (WAFs) with custom rules to detect and block OS command injection patterns targeting the vulnerable endpoint.
  5. Coordinate with NesterSoft Inc. for timely patch deployment once available; prioritize patching in all environments including cloud and on-premises.
  6. Conduct thorough security audits and penetration testing post-patching to ensure the vulnerability is fully remediated.
  7. Educate IT and security teams about this vulnerability to increase awareness and readiness to respond to potential exploitation attempts.
  8. Consider isolating or temporarily disabling the vulnerable functionality if patching or mitigation cannot be immediately implemented.

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.

References

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