How severe is CVE-2026-34211?

CVE-2026-34211 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-34211 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-34211?

CVE-2026-34211 affects Nyariv Sandboxjs. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-34211?

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

Does CVE-2026-34211 have an EU (EUVD) identifier?

Yes. CVE-2026-34211 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19299.

When was CVE-2026-34211 published?

CVE-2026-34211 was published on 2026-04-06 and last updated on 2026-06-17.

CVE-2026-34211

CVE-2026-34211 is a high-severity vulnerability in Nyariv Sandboxjs with a CVSS 3.x base score of 7.5. 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-674.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 6.9
EPSS exploit prediction: 0% (32nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-19299
Weakness: CWE-674
Affected product: Nyariv Sandboxjs
Published: 2026-04-06
Last modified: 2026-06-17

Description

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, the @nyariv/sandboxjs parser contains unbounded recursion in the restOfExp function and the lispify/lispifyExpr call chain. An attacker can crash any Node.js process that parses untrusted input by supplying deeply nested expressions (e.g., ~2000 nested parentheses), causing a RangeError: Maximum call stack size exceeded that terminates the process. This vulnerability is fixed in 0.8.36.

Frequently asked questions

What is CVE-2026-34211?: SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, the @nyariv/sandboxjs parser contains unbounded recursion in the restOfExp function and the lispify/lispifyExpr call chain. An attacker can crash any Node.js process that parses untrusted input by supplying deeply nested expressions (e.g., ~2000 nested parentheses), causing a RangeError: Maximum call stack size exceeded that terminates the process. This vulnerability is fixed in 0.8.36.
How severe is CVE-2026-34211?: CVE-2026-34211 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-34211 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-34211?: CVE-2026-34211 affects Nyariv Sandboxjs. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-34211?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-34211 have an EU (EUVD) identifier?: Yes. CVE-2026-34211 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19299.
When was CVE-2026-34211 published?: CVE-2026-34211 was published on 2026-04-06 and last updated on 2026-06-17.

References

https://github.com/nyariv/SandboxJS/security/advisories/GHSA-8pfc-jjgw-6g26

Affected products (1)

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

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