What Magento Leaders Need to Know About Script Control for PCI DSS 4.0 Compliance

This article builds on our PCI DSS 4.0 Magento best practices overview and focuses on what ecommerce leaders need to understand about scripts on checkout and payment pages, and how this work plays out on Magento storefronts.

What changed with PCI DSS 4.0?

PCI DSS 4.0 increases expectations around scripts that run on checkout and payment pages. Merchants must be able to demonstrate control over the scripts that execute in the customer’s browser during checkout. This aligns with evolving threats where attackers inject or modify scripts to skim cardholder data.

For Magento, this means tightening Content Security Policy (CSP) enforcement on payment pages and reducing or better governing the set of third-party scripts that run there.

What your organization needs in place

Merchants generally need to show four outcomes for payment pages:

• A current inventory of all scripts: Identify everything running on checkout and payment pages, with a documented purpose for each.
• Authorization controls: Ensure only approved scripts can run, including limiting who may add or modify tags through GTM.
• Technical enforcement: Block unapproved scripts, most often through CSP.
• Monitoring and response: Detect and address unauthorized script changes quickly.

This is not only an engineering effort; it requires clear governance and predictable processes.

Where internal resources are typically needed

Security, compliance, or IT leadership defines scope and acceptance criteria. This includes which pages qualify as payment pages, which tools are allowed on those pages, and who has authority to approve changes.

Marketing and ecommerce operations determine which marketing tags are essential on checkout versus elsewhere, and coordinate with agencies so change control is consistent.

Engineering handles CSP configuration, third-party allowlisting, compatibility work with themes or modules, and end-to-end checkout testing.

QA and release management verify that changes do not introduce regressions in checkout flows, payment processing, or address and tax logic.

How IronPlane can help when internal resources aren't available

When internal bandwidth is limited, the most efficient approach is to handle this as a structured project.

Current-state audit

We identify the scripts and third-party endpoints running on checkout and payment pages, how they are introduced (Magento code, GTM, CMS blocks), and what may be at risk under strict CSP enforcement. The output is a prioritized plan focused on stability and compliance posture.

Implementation and remediation

We configure CSP enforcement, add the required allowlists by directive, and adjust themes or modules to avoid CSP-breaking patterns where possible. We also help clarify which tags should or should not run on checkout.

Testing and rollout support

We support regression testing across checkout flows and payment methods, and help plan a controlled rollout with monitoring and rollback options. After release, we tune policies based on CSP reports and observed behavior.

Ongoing governance support

For organizations with frequent marketing changes or heavy GTM usage, we help establish a light approval process for new scripts and maintain a list of checkout-approved tools and endpoints so changes do not create recurring disruptions.

Decisions leadership should make early

Two early decisions determine whether this becomes a manageable project or a recurring source of friction.

Whether marketing experimentation tools are allowed on checkout
Experimentation tools introduce dynamic script changes. Allowing them on checkout increases complexity and risk. Excluding them usually improves stability and simplifies compliance.

Who owns script approval on payment pages
Without clear ownership, GTM and third-party integrations can become uncontrolled change paths. Defined authority and documentation keep checkout stable and make compliance reviews more predictable.

What success looks like

Success is a checkout where only approved scripts run, CSP blocks unexpected execution, changes follow a controlled process, and monitoring catches issues early. This reduces emergency fixes, improves stability, and results in a compliance posture that is easier to defend.

Next article in the series

Next, we will cover why this work matters in practical terms, how to assess your current checkout script surface, how different sized organizations may approach the problem, and a field guide for deciding which tools belong in GTM versus Magento code, with checklists you can reuse.