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TI-2026-20921 Aliases CVE-2026-25881GHSA-ww7g-4gwx-m7wj

@nyariv/sandboxjs has host prototype pollution from sandbox via array intermediary (sandbox escape)

Priority MEDIUM 44CWE-1321Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub.

Summary

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.31, a sandbox escape vulnerability allows sandboxed code to mutate host built-in prototypes by laundering the isGlobal protection flag through array literal intermediaries. When a global prototype reference (e.g., Map.prototype, Set.prototype) is placed into an array and retrieved, the isGlobal taint is stripped, permitting direct prototype mutation from within the sandbox. This results in persistent host-side prototype pollution and may enable RCE in applications that use polluted properties in sensitive sinks (example gadget: execSync(obj.cmd)). This vulnerability is fixed in 0.8.31.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00613 49th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed SandboxJS (nyariv): 0.8.31@nyariv/sandboxjs (npm): 0.8.31

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
nyarivSandboxJSbefore 0.8.310.8.31Patch availableCNA
—@nyariv/sandboxjs (npm)before 0.8.310.8.31Patch availableGHSA-ww7g-4gwx-m7wj
  • SandboxJS Vendornyariv Affected before 0.8.31 Fixed in 0.8.31 Patch available CNA
  • @nyariv/sandboxjs (npm) Vendor— Affected before 0.8.31 Fixed in 0.8.31 Patch available GHSA-ww7g-4gwx-m7wj

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:nyariv:sandboxjs:*:*:*:*:*:node.js:*:*before 0.8.31Vulnerablenyariv
  • cpe:2.3:a:nyariv:sandboxjs:*:*:*:*:*:node.js:*:* Versions before 0.8.31 Vulnerable ·nyariv

Remediation

  • Fix · CNA SandboxJS (nyariv) Fixed in 0.8.31
  • Fix · GHSA-ww7g-4gwx-m7wj @nyariv/sandboxjs (npm) Fixed in 0.8.31 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-25881
  2. 2026-10-03 Alias added: GHSA-ww7g-4gwx-m7wj
  3. 2026-10-07 EPSS moved to the 50th–90th percentile
  4. 2026-10-25 EPSS moved to the below the 50th percentile

References

Exploit 1

Patch 1

Advisory 1

Other 1

  • TI-2026-31962 SandboxJS: Sandbox escape via Function.caller leakage of internal call op CVSS 3.1CRITICAL 10.0
  • TI-2026-26503 SandboxJS: Sandbox integrity escape CVSS 3.1CRITICAL 10.0
  • TI-2026-21440 SandboxJS has a Sandbox Escape CVSS 3.1CRITICAL 10.0
  • TI-2026-20741 SandboxJS has a sandbox escape via TOCTOU bug on keys in property accesses CVSS 3.1CRITICAL 10.0
  • TI-2026-20694 SandboxJS has a Sandbox Escape CVSS 3.1CRITICAL 10.0
  • TI-2026-20693 SandboxJS has a Sandbox Escape via Prototype Whitelist Bypass and Host Prototype Pollution CVSS 3.1CRITICAL 10.0
See all 12 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences