CVE-2026-12866
CRITICAL
NVD
CVSS Score
9.8
Severity
CRITICAL
Published
Jun 23, 2026
Vendor
unknown
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.