CVE-2026-4800
HighCVSS 8.1Exploitation Probability (EPSS)
High risk85th percentile - higher than 85% of all known CVEs
Summary
The fix for CVE-2021-23337 added validation for the variable option in _.template but did not apply the same validation to options.imports key names, and both paths flow into the same Function() constructor sink. When an application passes untrusted input as options.imports key names, an attacker can inject default-parameter expressions that execute arbitrary code at template compilation time. Additionally, _.template uses assignInWith to merge imports, which enumerates inherited properties via for..in, so if Object.prototype has been polluted by another vector the polluted keys are copied into the imports object and passed to Function().
Risk Assessment
An attacker can execute arbitrary code in the application context, leading to full system compromise if the application passes untrusted input as options.imports key names.
Recommendation
Update lodash, lodash-es, lodash-amd, and lodash.template to version 4.18.1 or later. As a workaround, do not pass untrusted input as key names in options.imports; use only developer-controlled, static key names.
Other vulnerabilities in lodash
See all- CVE-2021-23337High
Lodash versions prior to 4.17.21 are vulnerable to Command Injection via the template function.
- CVE-2020-28500Medium
Lodash versions prior to 4.17.21 are vulnerable to Regular Expression Denial of Service (ReDoS) via the toNumber, trim and trimEnd functions.
- CVE-2020-8203High
Prototype pollution attack when using _.zipObjectDeep in lodash before 4.17.20.
- CVE-2026-2950Medium
The _.unset and _.omit functions in Lodash are vulnerable to prototype pollution. The fix for CVE-2025-13465 only guards against string key members, so an attacker can bypass the check by passing array-wrapped path segments. This allows deletion of properties from built-in prototypes such as Object.prototype, Number.prototype, and String.prototype. The issue permits deletion of prototype properties but does not allow overwriting their original behavior. The issue is patched from 4.18.0 to 4.18.1 depending on the package: lodash, lodash-es, and lodash-amd in 4.18.1, and the standalone lodash.unset and lodash.omit packages in 4.18.0.
- CVE-2025-13465Medium
The _.unset and _.omit functions in Lodash are vulnerable to prototype pollution. An attacker can pass crafted paths which cause Lodash to delete methods from global prototypes. The issue permits deletion of properties but does not allow overwriting their original behavior. The issue is patched from 4.17.23 to 4.18.0 depending on the package: lodash, lodash-es, and lodash-amd in 4.17.23, and the standalone lodash.unset and lodash.omit packages in 4.18.0.
Original NVD description (English source)
The fix for CVE-2021-23337 added validation for the variable option in _.template but did not apply the same validation to options.imports key names, and both paths flow into the same Function() constructor sink. When an application passes untrusted input as options.imports key names, an attacker can inject default-parameter expressions that execute arbitrary code at template compilation time. Additionally, _.template uses assignInWith to merge imports, which enumerates inherited properties via for..in, so if Object.prototype has been polluted by another vector the polluted keys are copied into the imports object and passed to Function(). The issue is fixed in 4.18.1 for lodash, lodash-es, lodash-amd, and lodash.template. As a workaround, do not pass untrusted input as key names in options.imports; use only developer-controlled, static key names.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS