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CVE-2026-25520

Nyariv Sandboxjs remote code execution

10.0 CRITICALPublic exploitEPSS 0.89%
  1. Published6 Feb 2026

Description

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, The return values of functions aren't wrapped. Object.values/Object.entries can be used to get an Array containing the host's Function constructor, by using Array.prototype.at you can obtain the hosts Function constructor, which can be used to execute arbitrary code outside of the sandbox. This vulnerability is fixed in 0.8.29.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

Nyariv Sandboxjs< 0.8.29

Remediation

Fixed in
Nyariv Sandboxjs≥ 0.8.29

References

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Frequently asked

Is CVE-2026-25520 being actively exploited?

CVE-2026-25520 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.89%.

How severe is CVE-2026-25520?

CVE-2026-25520 has a CVSS 3.1 base score of 10.0, rated critical. EPSS estimates a 0.89% probability of exploitation.

Which products are affected by CVE-2026-25520?

Affected products include Nyariv Sandboxjs.

How do I fix CVE-2026-25520?

Upgrade affected software to a fixed version, for example Nyariv Sandboxjs 0.8.29 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-25520 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.