CVE-2026-4637Medium· 5.1▾ TwilightPoC availablePaessler 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 …
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 28.1 · likelihood 0 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Exploit / PoC code exists
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.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-4638High· 7.1PRTG Network Monitor before version 26.2.120.1449 ships a demo EXE/Script sensor that multiplies two integer parameters using cscript.exe
CVE-2023-28148High· 7.2A bodyclass XSS issue was discovered in Paessler PRTG before 23.3.86.1520.
CVE-2023-22631Low· 2.7PRTG Network Monitor before 23.1.82 allows remote attackers to write to files via the HTTP XML/REST Sensor.
CVE-2023-22632Low· 2.7PRTG Network Monitor before 23.1.82 allows remote attackers to write to files via the FTP Server Count Sensor.
CVE-2023-45858High· 8.6A directory traversal was identified in Paessler PRTG before 23.4.88.1429 that made it possible to read local files.
CVE-2021-41184Medium· 6.5jQuery-UI is the official jQuery user interface library