How severe is CVE-2026-25586?

CVE-2026-25586 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-25586 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25586?

CVE-2026-25586 affects Nyariv Sandboxjs. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25586?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-25586 have an EU (EUVD) identifier?

Yes. CVE-2026-25586 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5592.

When was CVE-2026-25586 published?

CVE-2026-25586 was published on 2026-02-06 and last updated on 2026-06-17.

CVE-2026-25586

CVE-2026-25586 is a critical-severity vulnerability in Nyariv Sandboxjs with a CVSS 3.x base score of 10.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-74.

Key facts

Severity: Critical (CVSS 3.x base score 10.0)
EPSS exploit prediction: 1% (46th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-5592
Weakness: CWE-74
Affected product: Nyariv Sandboxjs
Published: 2026-02-06
Last modified: 2026-06-17

Description

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, a sandbox escape is possible by shadowing hasOwnProperty on a sandbox object, which disables prototype whitelist enforcement in the property-access path. This permits direct access to __proto__ and other blocked prototype properties, enabling host Object.prototype pollution and persistent cross-sandbox impact. This vulnerability is fixed in 0.8.29.

Frequently asked questions

What is CVE-2026-25586?: SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, a sandbox escape is possible by shadowing hasOwnProperty on a sandbox object, which disables prototype whitelist enforcement in the property-access path. This permits direct access to __proto__ and other blocked prototype properties, enabling host Object.prototype pollution and persistent cross-sandbox impact. This vulnerability is fixed in 0.8.29.
How severe is CVE-2026-25586?: CVE-2026-25586 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-25586 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25586?: CVE-2026-25586 affects Nyariv Sandboxjs. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25586?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-25586 have an EU (EUVD) identifier?: Yes. CVE-2026-25586 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5592.
When was CVE-2026-25586 published?: CVE-2026-25586 was published on 2026-02-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nyariv:sandboxjs:*:*:*:*:*:node.js:*:*

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