FKIE_CVE-2026-4637

Vulnerability from fkie_nvd - Published: 2026-09-24 10:17 - Updated: 2026-09-24 20:43
Severity
5.1 (Medium) - 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
Summary
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.
References
551230f0-3615-47bd-b7cc-93e92e730bbfhttps://paessler.freshdesk.com/en/support/solutions/articles/76000088640
551230f0-3615-47bd-b7cc-93e92e730bbfhttps://r.sec-consult.com/paessler
551230f0-3615-47bd-b7cc-93e92e730bbfhttps://www.paessler.com/de/download/
551230f0-3615-47bd-b7cc-93e92e730bbfhttps://www.paessler.com/prtg/prtg-network-monitor
134c704f-9b21-4f2e-91b3-4a467353bcc0https://sec-consult.com/vulnerability-lab/advisory/multiple-vulnerabilities-in-paessler-prtg-network-monitor/
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "PRTG Network Monitor",
          "vendor": "Paessler GmbH",
          "versions": [
            {
              "lessThan": "26.2.120.1449",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "551230f0-3615-47bd-b7cc-93e92e730bbf"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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.\n\n\n\n\nAn 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\u0027s session cookie, potentially leading to session hijacking."
    }
  ],
  "id": "CVE-2026-4637",
  "lastModified": "2026-09-24T20:43:32.537",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 5.1,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "LOW",
          "userInteraction": "ACTIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "551230f0-3615-47bd-b7cc-93e92e730bbf",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-4637",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-24T12:19:37.419469Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-24T10:17:37.813",
  "references": [
    {
      "source": "551230f0-3615-47bd-b7cc-93e92e730bbf",
      "url": "https://paessler.freshdesk.com/en/support/solutions/articles/76000088640"
    },
    {
      "source": "551230f0-3615-47bd-b7cc-93e92e730bbf",
      "url": "https://r.sec-consult.com/paessler"
    },
    {
      "source": "551230f0-3615-47bd-b7cc-93e92e730bbf",
      "url": "https://www.paessler.com/de/download/"
    },
    {
      "source": "551230f0-3615-47bd-b7cc-93e92e730bbf",
      "url": "https://www.paessler.com/prtg/prtg-network-monitor"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://sec-consult.com/vulnerability-lab/advisory/multiple-vulnerabilities-in-paessler-prtg-network-monitor/"
    }
  ],
  "sourceIdentifier": "551230f0-3615-47bd-b7cc-93e92e730bbf",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ],
      "source": "551230f0-3615-47bd-b7cc-93e92e730bbf",
      "type": "Secondary"
    }
  ]
}



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