How severe is CVE-2026-25520?

CVE-2026-25520 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-2026-25520 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25520?

CVE-2026-25520 affects Nyariv Sandboxjs. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25520?

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-2026-25520 have an EU (EUVD) identifier?

Yes. CVE-2026-25520 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5591.

When was CVE-2026-25520 published?

CVE-2026-25520 was published on 2026-02-06 and last updated on 2026-06-17.

CVE-2026-25520

CVE-2026-25520 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% (52nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-5591
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, 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.

Frequently asked questions

What is CVE-2026-25520?: 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.
How severe is CVE-2026-25520?: CVE-2026-25520 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-2026-25520 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25520?: CVE-2026-25520 affects Nyariv Sandboxjs. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25520?: 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-2026-25520 have an EU (EUVD) identifier?: Yes. CVE-2026-25520 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5591.
When was CVE-2026-25520 published?: CVE-2026-25520 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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