How severe is CVE-2026-25881?

CVE-2026-25881 has a CVSS 3.x base score of 9.0, rated critical severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-25881 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25881?

CVE-2026-25881 affects Nyariv Sandboxjs. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25881?

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-2026-25881 have an EU (EUVD) identifier?

Yes. CVE-2026-25881 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6864.

When was CVE-2026-25881 published?

CVE-2026-25881 was published on 2026-02-09 and last updated on 2026-06-17.

CVE-2026-25881

CVE-2026-25881 is a critical-severity vulnerability in Nyariv Sandboxjs with a CVSS 3.x base score of 9.0. 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-1321.

Key facts

Severity: Critical (CVSS 3.x base score 9.0)
EPSS exploit prediction: 1% (42nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-6864
Weakness: CWE-1321
Affected product: Nyariv Sandboxjs
Published: 2026-02-09
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-25881?: 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.
How severe is CVE-2026-25881?: CVE-2026-25881 has a CVSS 3.x base score of 9.0, rated critical severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-25881 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25881?: CVE-2026-25881 affects Nyariv Sandboxjs. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25881?: 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-2026-25881 have an EU (EUVD) identifier?: Yes. CVE-2026-25881 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6864.
When was CVE-2026-25881 published?: CVE-2026-25881 was published on 2026-02-09 and last updated on 2026-06-17.

References

Affected products (1)

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

More vulnerabilities in Nyariv Sandboxjs

CVE-2026-43898 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.9.6, sandbox-defined functions expose Function.caller,…
CVE-2026-34208 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, SandboxJS blocks direct assignment to global objects…
CVE-2026-26954 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.34, it is possible to obtain arrays containing Function,…
CVE-2026-25641 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, there is a sandbox escape vulnerability due to a…
CVE-2026-25587 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, as Map is in SAFE_PROTOYPES, it's prototype can be…
CVE-2026-25586 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, a sandbox escape is possible by shadowing hasOwnProperty…

All CVEs affecting Nyariv Sandboxjs →

Other CWE-1321 (Prototype Pollution) vulnerabilities

CVE-2026-25142 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.27, SanboxJS does not properly restrict __lookupGetter__…
CVE-2024-39008 — Critical (CVSS 10.0): robinweser fast-loops v1.1.3 was discovered to contain a prototype pollution via the function objectMergeDeep. This…
CVE-2024-38999 — Critical (CVSS 10.0): jrburke requirejs v2.3.6 was discovered to contain a prototype pollution via the function s.contexts._.configure. This…
CVE-2022-29823 — Critical (CVSS 10.0): Feather-Sequalize cleanQuery method uses insecure recursive logic to filter unsupported keys from the query object.…
CVE-2022-24760 — Critical (CVSS 10.0): Parse Server is an open source http web server backend. In versions prior to 4.10.7 there is a Remote Code Execution…
CVE-2020-12079 — Critical (CVSS 10.0): Beaker before 0.8.9 allows a sandbox escape, enabling system access and code execution. This occurs because Electron…

Browse all CWE-1321 (Prototype Pollution) vulnerabilities →