CVE-2026-12866: Code Injection

Published Jun 23, 2026
·
Updated

All versions of the package expr-eval are vulnerable to Code Execution via the toJSFunction() API. An attacker can execute arbitrary JavaScript by supplying crafted expressions that are compiled into native code using new Function(). Because user-controlled expressions are transformed directly into executable JavaScript, attackers can escape the intended expression sandbox and run arbitrary code within the application's context.

Affected Software

1 affected component
npm/expr-eval>=0

Event History

Jun 23, 2026
CVE Published
via MITRE·05:00 AM
Data Sourced
via MITRE·05:00 AM
DescriptionSeverityWeakness
Data Sourced
via NVD·05:17 AM
DescriptionSeverityWeakness
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Frequently Asked Questions

1

What is the severity of CVE-2026-12866?

CVE-2026-12866 has a critical severity rating of 9.8.

2

How does CVE-2026-12866 allow for code execution?

CVE-2026-12866 allows for code execution through the toJSFunction() API, where crafted expressions can execute arbitrary JavaScript.

3

Which versions of expr-eval are affected by CVE-2026-12866?

All versions of the expr-eval package are affected by CVE-2026-12866.

4

What is the risk level associated with CVE-2026-12866?

CVE-2026-12866 is rated with a risk level of 86.

5

How can I mitigate the risks of CVE-2026-12866?

To mitigate the risks of CVE-2026-12866, upgrade to a patched version of the expr-eval package.

Company

Resources

Contact

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CVE-2026-12866 - Code Injection - SecAlerts