CVE-2026-4637

Paessler PRTG Network Monitor before version 26.2.120.1449 is affected by a reflected Cross-Site Scripting (XSS) vulnerability. When a request is made for a non-existent resource ending in \".htm\", the web interface returns an HTTP 403 \"Forbidden Path\" error page that echoes the requested URL path into the HTML response body without proper output encoding or sanitization. An unauthenticated, remote attacker can craft a URL containing an HTML/JavaScript payload in the path (e.g. https:////welcome.htm) and, once a victim with an active PRTG session opens the crafted link, execute arbitrary JavaScript in the security context of the PRTG web interface. Because the PRTG session cookie is not protected with the HttpOnly attribute, successful exploitation allows the attacker to read and exfiltrate the victim's session cookie, potentially leading to session hijacking.

CVSS

No CVSS.

References

Link	Resource
https://paessler.freshdesk.com/en/support/solutions/articles/76000088640
https://r.sec-consult.com/paessler
https://www.paessler.com/de/download/
https://www.paessler.com/prtg/prtg-network-monitor
https://sec-consult.com/vulnerability-lab/advisory/multiple-vulnerabilities-in-paessler-prtg-network-monitor/

Configurations

No configuration.

History

24 Sep 2026, 13:17

Type	Values Removed	Values Added
References		() https://sec-consult.com/vulnerability-lab/advisory/multiple-vulnerabilities-in-paessler-prtg-network-monitor/ -

24 Sep 2026, 10:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-24 10:17

Updated : 2026-09-24 20:43

NVD link : CVE-2026-4637

Mitre link : CVE-2026-4637

CVE.ORG link : CVE-2026-4637

JSON object : View

Products Affected

No product.

CWE

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

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