Vulnerability in Paessler GmbH PRTG Network Monitor

[ Description ]Official description

PRTG Network Monitor before version 26.2.120.1449 ships a demo EXE/Script sensor that multiplies two integer parameters using cscript.exe. If a non-numeric value is passed instead, cscript.exe raises a 'Type mismatch' runtime error that includes the offending parameter value in plaintext. PRTG provides a documented placeholder variable, %windowspassword, which resolves to the configured Windows/domain password used by PRTG and can be passed as a sensor parameter.  Any PRTG user who is not restricted to read-only access and is permitted to create sensors (the default for non-read-only users) can pass %windowspassword as an argument to the demo VBScript sensor, triggering the type-mismatch error and causing PRTG to display the plaintext password in the sensor's error output.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund23 Sep 2026WID-SEC-2026-3565

  Paessler PRTG: Multiple vulnerabilities Translated from German

  CVE-2026-4638CVE-2026-4637

[ References ]References

• paessler.freshdesk.com/en/support/solutions/articles/76000088640
• r.sec-consult.com/paessler
• www.paessler.com/de/download
• www.paessler.com/prtg/prtg-network-monitor