CVE-2026-12866NVD

Vulnerability Summary

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.

Severity Level

CRITICAL(9.8)

Published Date

Jun 23, 2026

Last Modified

Sep 22, 2026

Exploitation Status

No confirmed exploitation yet

EPSS Score (30-Day)

0.87%Probability

Root Weakness (CWE)

CWE-94: Code Injection ↗

The software constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended syntax or behavior.

CVSS v4.0 Base Metrics — Score 9.2

Attack VectorNetwork

Attack ComplexityLow

Attack RequirementsPresent

Privileges RequiredNone

User InteractionNone

Confidentiality (Vulnerable System)High

Integrity (Vulnerable System)High

Availability (Vulnerable System)High

Confidentiality (Subsequent System)None

Integrity (Subsequent System)None

Availability (Subsequent System)None

CVSS v3.1 Base Metrics — Score 9.8

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

Affected & Patched Versions

Affected Versions

expr-eval <= 2.0.2
org.webjars.npm:expr-eval <= 2.0.2

Patched Versions

Not provided by Private for this CVE.

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