Common PCI DSS Compliance Mistakes

Last Updated on January 7, 2026 by Narendra Sahoo

PCI DSS compliance requires an organizational implementation of the required processes and procedures. Your compliance efforts are typically sabotaged by mistakes made from the top.

We’re going to briefly discuss the top PCI DSS Compliance Mistakes that are made and how to avoid them.

In our projects, we have seen that most PCI failures are not technical. Most of the failures originate from PCI ownership not being implemented at an executive level. It also occurs when security is treated as an audit exercise, not an operational and business reality. Subsequently, assuming risk as opposed to managing it, with compliance being delegated without authority results in a return to vision, governance, accountability, and covering organizational blind spots. Allocating your resources towards these helps prevent most PCI failures: governance and scoping decide outcomes.

Data Breaches and PCI Compliance Risks

For many companies, one popular trope regarding breaches is that it’s not a matter of if but when a data breach happens, and data breaches are expensive. A PCI DSS Scoping and Data Discovery work to define the cardholder’s data environment via systematically identifying, validating, continuously monitoring all systems, networks and data flows for storing, processing or transmitting cardholder data.

There are fines and remediation costs, but the most serious cost is the damage to the trust you have worked so hard to build with your customers.

Mistake #1: Not Knowing Your Overall PCI DSS Scope

The number one critical mistake is not knowing your overall PCI DSS scope.

Many organizations have scattered systems and storage networks and haven’t conducted a thorough inventory of where cardholder data is.

Systems that have a communication path to where the cardholder data is stored or processed must be included as in-scope systems, including directory and authentication servers, domain name servers, patch deployment servers, and wireless connectivity.

Key Scoping Principle

Any system with a communication path, administrative access, or data flow relationship to cardholder data must be considered in scope—regardless of whether its “stores” card data directly.

Many organizations therefore need systems or software to look behind the scenes, scouting out and discovering previously unknown cardholder data locations.

The goal is to leave no stone unturned and reduce the chance that there is potentially unsecured payment card information that might be compromised.

That’s why starting with data discovery is the best foundation for driving PCI DSS compliance.

We advice our clients that for avoiding most compliance failures, comprehensive scoping is the fundamental starting point. The work in scoping effectively serves as a foundation to define the cardholder data environment (CDE). Scoping is step one because it decides what exactly needs to be protected. If you draw the boundary wrong, you either miss systems that handle card data (creating risk) or include too many systems (creating unnecessary cost and complexity). This is where they realize:

• Leadership doesn’t know where CHD/SAD lives
• Systems with indirect access were “forgotten”
• PCI scope is either dangerously too small or explosively large

This is why senior consultants repeatedly say: “If scoping is wrong, everything downstream fails.”

Mistake #2: Failing to Maintain an Accurate Inventory

This brings us to our second biggest mistake, which is related to the PCI DSS requirement to maintain an inventory of system components that are in scope for PCI DSS.

If your organization fails to keep an up-to-date inventory of all your software and hardware components that are in scope, then ensuring compliance will be a difficult task.

PCI DSS also requires preservation of access logs.

Keeping a meticulous record of your hardware and software catalog and access information will not only satisfy the PCI DSS requirements but also help you maintain a high level of understanding of how your data is being processed and who has access to it.

To address this issue, our consultants value comprehensive outlines of architectures, flows, and paths to SAD and CHD for PCI DSS. A PCI DSS inventory includes all system components remaining in scope for cardholder data environment (CDE). That includes all hardware and software components storing processing or transmitting cardholder data (CHD), regardless of an organization’s size.

To ensure a comprehensive inventory and avoid compliance failures, the following systems must be included:

VISTA InfoSec: PCI DSS Scoping — Systems and Assets to Be Included

Category	System Type	Description / Inclusion Criteria
1. Systems Directly Involved with Cardholder Data	Storage, Processing, and Transmission Systems Storage, Processing, and Transmission Systems	Any system that directly stores, processes, or transmits Cardholder Data (CHD) or Sensitive Authentication Data (SAD). Storage locations that may contain residual card data, including logs, databases, backups, and file shares. Any application or API that transmits cardholder data, including indirect or undocumented data flows.
2. Connected and Security-Impacting Systems	Infrastructure Services Wireless Connectivity Components Security Systems	Systems with a communication path or administrative relationship to the CDE, such as directory services, authentication servers, DNS, and patch management servers. All systems and components that provide wireless access to the environment. Systems supporting multifactor authentication (MFA) and managing remote or administrative access to critical systems.
3. Support and Access Endpoints	Support Desktops Jump Hosts Batch Servers	End-user or support workstations with access paths to the Cardholder Data Environment (CDE). Intermediate systems used to access CDE systems for administration or support. Servers used for scheduled or automated processing with access to the CDE.
4. Impacted “Non-CDE” Systems Ongoing Compliance Requirement	Flat Network Segments Third-Party Connections Asset Inventory and Access Records	Non-CDE systems that become in-scope due to inadequate network segmentation and direct network access to CDE systems. Systems enabling third-party or vendor access into the payment or cardholder data environment. Organizations must maintain accurate, up-to-date inventories of all hardware and software assets, including access details, to understand how cardholder data is processed and who can access it.

Mistake #3: Not Supporting Teams with Effective Policies and Procedures

The third biggest mistake ties it all together.

It’s simply not setting your team up for success with detailed and efficient policies and procedures throughout the year that will facilitate compliance smoothly.

Things like documentation requirements need to be considered far in advance rather than scrambling to piece them all together at the last minute.

We always recommend clients to first get the strategy in place, document the strategy into policies, procedures and SOPs, then implement the developed SOPs, then at regular intervals check whether the system is working fine and update the documentation as needed… it’s a very bad strategy to first implement processes and then document what has been implemented.

Mistake #4: Thinking Your Organization Won’t Make Mistakes

When it comes to PCI compliance, even the smartest organizations make mistakes, risking their money and customer relationships.

We’re here to help you avoid some of these mistakes.

Underestimating the likelihood of experiencing a data breach and failing to put a response plan in place is an unforced error that you don’t have to make.

While you should do everything in your power to prevent a data breach from happening, you should also be prepared to act quickly if it happens.

Key that we always tell our clients is that “Absence of any evidence of mistakes does not mean that there have been no mistakes… without a well-defined review cycle in place, it’s very well possible that mistakes happened but have never been identified and worked on”

Mistake #5: PCI Compliance Isn’t Core to Your Business Plan

Forward-thinking companies don’t just meet the minimum requirements. Making Organizational Governance in PCI Compliance a primary aim among your operational capabilities is key to attaining business continuity and success.

They turn PCI compliance into a competitive or strategic advantage.

It’s possible to improve customer experience while reducing your PCI scope with self-service tools that make it easy for customers to enter their own data whenever possible.

Even if you minimize PCI compliance mistakes and are still impacted, the average cost of a data breach is 15% over 3 years.

Mistake #6: Ignoring Third-Party Risks

If you use third-party service providers, don’t overlook their compliance status.

Their adherence to PCI compliance impacts your organization’s data security.

In addition, legacy or outdated systems can make it more challenging to meet PCI DSS requirements.

Mistake #7: Mishandling Cardholder Data

Companies are often observed holding and storing cardholder data unnecessarily, not following best practices like tokenization, and even writing credit card numbers on sticky notes.

A solid rule of thumb is: Hear no card data, see no card data, touch no card data unless explicitly required for processing.

Mistake #8: A Set-It-and-Forget-It Approach

PCI compliance is an ongoing process, not a one-time event.

Regular security testing and employee training make sure that the plans and processes you put in place keep working to protect your organization and your customers.

Our auditors see these mistakes most clearly when:

• QSAs request evidence, not policies
• Auditors rely on just personnel feedback instead of testing actual system behavior
• Access reviews, logs, and segmentation are not validated

Common moments of failure:

• “We encrypt data” → backups aren’t encrypted
• “Only limited users have access” → shared admin accounts
• “Vendors are compliant” → no contracts, no monitoring

This is where performative security is exposed.

Mistake #9: Improper Segmentation and Scoping

Networks and systems that handle and carry cardholder data may not be properly segmented and separated from the rest of the network.  Improper segmentation and scoping expand the attack surface, leaves vulnerabilities open and undetected, and is a prime cause for data breaches and leaks of CHD and SAD.

Segmentation is not a mandate under PCI DSS, but we always advise our clients that this is the best and most efficient way to ensure that scope is limited, exposure to breach is limited, and cost of compliance is minimized.

Mistake #10: Failing to Change Vendor Defaults

Next, failing to change vendor defaults is another mistake.

Using default passwords or security settings provided by vendors can create vulnerabilities.

These defaults are often well known and can be easily exploited.

Always change default credentials and configure security settings to build a secure network.

Using vendor default settings is akin to purchasing a high-end security safe but leaving the combination as “0000”. While the safe provides robust security, its factory-set code is public knowledge. Without changing your vendor’s defaults to your unique combinations, these systems provide no real protection.  Experienced cybersecurity consultants and auditors often notice these issues prior to testing controls.

Mistake #11: Assuming PCI DSS Does Not Apply

Some businesses mistakenly assume that payment card industry data security standards do not apply to them if they do not store card data or think they are too small. However, these rules apply to any business that processes, stores, or transmits cardholder data regardless of size.

Mistake #12: Completing the Wrong Self-Assessment Questionnaire (SAQ)

Another common error is completing the wrong self-assessment questionnaire.

This questionnaire must match your payment processing environment.

Selecting the incorrect one can led to non-compliance.

Make sure you understand your payment setup and choose the correct self-assessment questionnaire to address all relevant controls.

We always recommend to our clients that instead of guessing which SAQ applies to them, are your client or Payment Acquirer or Payment Brand. We have seen multiple clients who think that they are covered under an SAQ, then engage us to complete their SAQ since their transactions are minimal but then the acquirer insists on a full L1 ROC since the risk profile of our client is high.

Mistake #13: Over-Reliance on Vulnerability Scanning

Relying solely on vulnerability scanning is also a mistake.

While scanning is required, relying only on automated scans without thorough penetration testing can leave gaps.

Proper testing should include manual assessments and validation of controls.

We have seen that Requirement 11 of PCI DSS covers the Vulnerability Assessment requirements in a very cohesive and comprehensive manner. Instead of guessing the rules of the game, we always recommend our clients to refer to this requirement of PCI DSS.

Mistake #14: Poor Data Storage and Transfer Practices

Mismanagement of data storage and transfer is another area of concern.

Payment card industry data security standards discourage storing sensitive payment data like card verification values or expiration dates.

Improper storage increases risk.

Additionally, transferring card data insecurely can expose it to interception.

Follow strict requirements for secure storage, encryption, and data minimization.

Mistake #15: Neglecting Multifactor Authentication (MFA)

Lastly, neglecting multifactor authentication can leave accounts vulnerable.

Failing to implement multifactor authentication for accessing systems that handle cardholder data can lead to unauthorized access.

Payment card industry data security standards require remote access and administrative access to critical systems.

For small businesses and startups, understanding these common mistakes is vital.

Properly scope your payment card industry data security standard requirements, secure all access points, and maintain ongoing compliance efforts.

Mistake #16: Not conducting proper risk assessment for cardholder data.

Not knowing where the majority of actual Cardholder Data Security Risks arise from. The following table outlines the most common PCI DSS scoping gaps and risk areas.

Common PCI DSS Scoping Gaps and Risk Areas

Scoping Gap	Typical Cause	Why It Expands PCI DSS Scope	Why It Expands PCI DSS Scope
Undocumented data flows between applications, APIs, and third-party services	Organic system growth, rapid integrations, poor data-flow documentation	Any system that transmits cardholder data, even indirectly, becomes in-scope	Cardholder data traverses unmonitored paths, increasing exposure and audit failure risk
Residual cardholder data in logs, databases, backups, and file shares	Debug logging, legacy retention policies, uncontrolled backups	Storage locations containing cardholder data are automatically included in scope	Hidden data stores create blind spots and long-term breach exposure
Over-privileged access to systems within or connected to the CDE	Role sprawl, lack of access reviews, shared admin credentials	Users and systems with excessive permissions are considered part of the CDE trust boundary	Increased insider risk and lateral movement during compromise
Flat network segments allowing non-CDE systems to access cardholder data systems	Inadequate network segmentation, legacy architecture	Non-CDE systems with network access inherit PCI scope requirements	Scope explosion and weakened containment during security incidents
Insecure endpoints (support desktops, jump hosts, batch servers) with access to payment data	Operational convenience, lack of hardening standards	Endpoints with access paths to the CDE must be treated as in-scope systems	Endpoints with access paths to the CDE must be treated as in-scope systems
Uncontrolled third-party connectivity into payment environment	Vendor access granted without formal governance or monitoring	Vendor access granted without formal governance or monitoring	Dependency risk, reduced visibility, and shared responsibility failures

Conclusion

Ultimately, PCI DSS compliance failures are rarely the result of technical gaps alone, but instead stem from organizational blind spots, weak governance, and misplaced assumptions at the leadership level. Making PCI compliance an ongoing, organizational operational requirement helps avoid some of the issues. Ultimately, the most common PCI DSS compliance mistakes are prevented by having a vision and thorough scoping.

A  leadership vision defines why PCI exists in the business, sets expectation for behavior, and fosters accountability across functions. Thorough scoping is key for preventing blind spots from turning into breaches.

Ultimately, the most common PCI DSS compliance mistakes are avoided when organizations combine clear leadership vision with thorough, evidence-based scoping.

Getting PCI DSS Compliance Right for Your Organization

Searching for Ongoing PCI DSS Compliance Management? What does it mean for your unique organization? Whether a merchant, vendor, or a service provider: VISTA InfoSec is your trusted partner.

When you start a PCI DSS compliance journey, we advise you on a customized workflow solution that will ensure each requirement is satisfied every step of the way, and we’ll verify each item along with you.

Especially if you’re an enterprise that processes cardholder data at multiple locations or a combination of online and brick and mortar, it can be increasingly difficult to get everyone on your team in synergy, and we provide tailored solutions for that.

Let us know how we can help you with your unique PCI DSS compliance needs.

If PCI DSS is your goal, VISTA InfoSec is your partner to get it done right.

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