CVE-2026-4637
Paessler PRTG Network Monitor before version 26.2.120.1449 is affected by a reflected Cross-Site Scripting (XSS) vulnerability.
Overview
CVE-2026-4637 is a known-severity vulnerability. It was published on September 24, 2026.
Technical description
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.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How CyberStrike helps
Reason, not just scan
It reasons through your app's logic the way a human pentester would, so it finds flaws signature scanners miss.
Learn moreVerified findings
Every finding is proven exploitable before you see it, which cuts the false positives that bury real risk.
Learn moreAI-driven DAST and SAST
Probe running apps and read source from one engine, so issues are caught before and after they ship.
Learn moreOpen source
Read exactly how it tests and what it reports. CyberStrike is open source and in early access.
View the repo
Frequently asked questions
What is CVE-2026-4637?
CVE-2026-4637 is a known-severity vulnerability. It was published on September 24, 2026.
How severe is CVE-2026-4637?
CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.
How do I fix or remediate CVE-2026-4637?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-4637?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-4637 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.