CVE-2026-4637
Reflected Cross-Site Scripting via URL Path in Paessler PRTG Network Monitor
- Published
- Updated
- Reserved
- Assigned by
- SEC-VLab
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| SEC-VLabCNA (assigner) | 4.0 | Medium5.1 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N |
| NVDNVD · Deferred | 4.0 | Medium5.1 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.60% · top 51% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.1.
Weakness
Affected products
Paessler GmbH · PRTG Network Monitor
- affected < 26.2.120.1449
What to do
Solution: Upgrade to Paessler PRTG Network Monitor version 26.2.120.1449 or later.
References (5)
- https://paessler.freshdesk.com/en/support/solutions/articles/76000088640 (opens in a new tab)vendor-advisory
- https://www.paessler.com/de/download/ (opens in a new tab)patch
- https://www.paessler.com/prtg/prtg-network-monitor (opens in a new tab)product
- https://r.sec-consult.com/paessler (opens in a new tab)third-party-advisory
- https://sec-consult.com/vulnerability-lab/advisory/multiple-vulnerabilities-in-paessler-prtg-network-monitor/ (opens in a new tab)exploit
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-4637)Record last updated .