Vulnerability Description
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.
CVSS Score
CRITICAL
Related Weaknesses (CWE)
References
- https://github.com/silentmatt/expr-eval/blob/master/src/expression.js%23L55
- https://github.com/silentmatt/expr-eval/issues/292
- https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-17662018
- https://security.snyk.io/vuln/SNYK-JS-EXPREVAL-15054690
- https://security.snyk.io/vuln/SNYK-JS-EXPREVAL-15054690
FAQ
What is CVE-2026-12866?
CVE-2026-12866 is a vulnerability with a CVSS score of 9.8 (CRITICAL). 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 ...
How severe is CVE-2026-12866?
CVE-2026-12866 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-12866?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.