Vulnerability · Published Sep 24, 2026 · Assigned by SEC-VLab
CVE-2026-4638Plaintext Password Disclosure via VBScript Sensor Error Message in Paessler PRTG Network Monitor
High 7.1
In plain English
A high-severity security flaw in PRTG Network Monitor from Paessler GmbH. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities).
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Paessler GmbH | PRTG Network Monitor | 0 – before 26.2.120.1449 |
Weakness: CWE-209 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
References
- https://r.sec-consult.com/paessler third-party-advisory
- https://paessler.freshdesk.com/en/support/solutions/articles/76000088640 vendor-advisory
- https://www.paessler.com/de/download/ patch
- https://www.paessler.com/prtg/prtg-network-monitor product