dbcve.org
SandboxjsApplication · Nyariv

CVE-2026-43898

CRITICAL · 10.0 CVSS v3.1 Published 2026-05-28
Fix available
A fix is available. Upgrade to 0.9.6 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
SandboxJS is a JavaScript sandboxing library. Prior to 0.9.6, sandbox-defined functions expose Function.caller, allowing sandboxed code to recover the internal LispType.Call runtime callback. That callback can then be invoked with attacker-controlled fake context and obj values to extract blocked host statics, recover the real host Function constructor, and execute arbitrary host JavaScript. This vulnerability is fixed in 0.9.6.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

SandboxJS prior to 0.9.6 has a sandbox escape vulnerability where sandbox-defined functions expose Function.caller, allowing malicious sandboxed code to recover the internal LispType.Call runtime callback. This callback can be invoked with attacker-controlled context and obj values to extract blocked host statics, recover the real host Function constructor, and achieve arbitrary host JavaScript execution.

MitigationUpgrade to SandboxJS version 0.9.6 or later to obtain the patch that removes Function.caller exposure of the internal LispType.Call callback.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SandboxjsApplication
Affected:< 0.9.6

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify SandboxJS installation and version
    Check your package.json, package-lock.json, or node_modules for the installed version of sandboxjs (may be listed as 'sandboxjs', '@nyariv/sandboxjs', or similar). Compare this version against the vulnerable range: versions prior to 0.9.6 are affected.
    Affected if The installed version is lower than 0.9.6 (e.g., 0.9.5, 0.9.0, etc.)
  2. Determine if sandbox-defined functions are used
    Search your codebase for patterns where sandbox-defined functions are created or where sandbox code defines functions that could access Function.caller. Look for code that executes untrusted JavaScript within the sandbox.
    Affected if Your application executes untrusted JavaScript in SandboxJS and that code can define or call functions that access Function.caller
  3. Verify Function.caller is accessible from sandboxed code
    Run a test with a sandboxed function that attempts to access its own caller property (e.g., (function(){ return arguments.callee.caller; })()). Evaluate this inside the sandbox context and observe whether the internal LispType.Call callback is exposed.
    Affected if Sandboxed functions can access Function.caller and recover the internal LispType.Call runtime callback, enabling further privilege escalation

You are affected if your environment runs SandboxJS version lower than 0.9.6 and executes untrusted code that can define or call functions accessing Function.caller within the sandbox context.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 0.9.6 or later
Fixed in 0.9.6
Vendor patch github.com →
Interim mitigation

Upgrade to SandboxJS version 0.9.6 or later to obtain the patch that removes Function.caller exposure of the internal LispType.Call callback.

Recommended fix High confidence

0.9.6

  1. Check the current version of sandboxjs in your project by running `npm list sandboxjs` or checking package.json
  2. Update sandboxjs to version 0.9.6 by running `npm install [email protected]` (or `yarn add [email protected]` / `pnpm add [email protected]`)
  3. Verify the upgrade was successful by running `npm list sandboxjs` and confirming version 0.9.6 is installed
  4. Test your application to ensure the sandbox functionality still works correctly with the updated library
  5. Rebuild and redeploy any services that depend on sandboxjs

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Sandboxjs Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing4.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,540
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,464.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-43898 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data