---
title: "Handlebars – Remote-code-execution Exploits Where Misusing The Helper blockHelperMissing On Versions Under 4.3.0"
description: "**Impact area** Security **Severity** High **Affected element** **ServiceNow** UI Script **Salesforce** Static Resource ## Rule number **SN-JSL-HANDLEBARS-LESSTHAN-V430 **(for ServiceNow) **SF-JSL-HANDLEBARS-LESSTHAN-V430 **(for Salesforce) ## Impact Calling \"helperMissing\" and \"blockHelperMissing\" directly from a template (like in {{blockHelperMissing}} was never intended and was part of…"
url: "https://community-staging.qualityclouds.com/qcdocs/qc/vulnerabilities-in-open-source-libraries-salesforce/handlebars-remote-code-execution-exploits-where-misusing-the-helper-blockhelpermissing-on-versions-under-4-3-0/"
updated: "2025-03-21"
category: Rules
---

# Handlebars – Remote-code-execution Exploits Where Misusing The Helper blockHelperMissing On Versions Under 4.3.0

**Impact area**

Security

**Severity**

High

**Affected element**

**ServiceNow**

UI Script

**Salesforce**

Static Resource

## Rule number

**SN-JSL-HANDLEBARS-LESSTHAN-V430 **(for ServiceNow)

**SF-JSL-HANDLEBARS-LESSTHAN-V430 **(for Salesforce)

## Impact

Calling "helperMissing" and "blockHelperMissing" directly from a template (like in {{blockHelperMissing}} was never intended and was part of the exploits that have been revealed early in 2019. It is also part of a new exploit that is not captured by the earlier fix.

Remediation

Update the Handlebars JS library to the latest version.

### Time to fix

30 min

## References

This rule is linked to [Common Weakness Enumeration CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')](https://cwe.mitre.org/data/definitions/79.html).