Internal Vulnerability Scans

PCI DSS requires you to run internal vulnerability scans at least once every three months, fix all high-risk and critical findings based on your vulnerability risk ranking method, and perform rescans that confirm those issues are closed. Your scanning tool must be current, scans must be run by qualified personnel, and the tester must have organizational independence. (PCI DSS v4.0.1 Requirement 11.3.1)

Key takeaways:

• Run internal vulnerability scans on a defined quarterly cadence and keep proof of execution. (PCI DSS v4.0.1 Requirement 11.3.1)
• Treat “pass” as “high-risk/critical fixed and verified by rescan,” not “scan completed.” (PCI DSS v4.0.1 Requirement 11.3.1)
• Maintain scanner currency, staff qualification, and tester independence as auditable control elements. (PCI DSS v4.0.1 Requirement 11.3.1)

“Internal vulnerability scans requirement” usually fails in practice for one of two reasons: (1) teams treat scanning as a security activity without making it an auditable compliance control, or (2) they scan, but they cannot prove that high-risk and critical vulnerabilities were resolved and verified by rescan. PCI DSS 4.0.1 closes those gaps by making the operational end-state explicit: scan quarterly, remediate high-risk and critical issues per your defined risk rankings, and rescan to confirm closure, using a current tool, run by qualified and independent personnel. (PCI DSS v4.0.1 Requirement 11.3.1)

For a CCO, GRC lead, or compliance owner, the fastest path is to treat this as a workflow control with tight evidence: scope definition for the cardholder data environment (CDE) and connected systems, an immutable quarterly scan schedule, documented risk ranking criteria, remediation SLAs tied to “high/critical,” and a rescan gate that blocks “closure” until verification exists. The rest is packaging: artifacts, exceptions, and independence attestations that a QSA can test quickly.

Regulatory text

Requirement (operator view). PCI DSS states: internal vulnerability scans must be performed at least once every three months; high-risk and critical vulnerabilities (as determined by the entity’s vulnerability risk rankings) must be resolved; rescans must confirm that all high-risk and critical vulnerabilities have been resolved; the scan tool is kept up to date; scans are performed by qualified personnel; and organizational independence of the tester exists. (PCI DSS v4.0.1 Requirement 11.3.1)

What an assessor will test. Expect testing to focus on three questions:

1. Did you scan the right in-scope assets on the required cadence? (PCI DSS v4.0.1 Requirement 11.3.1)
2. Did you close every high/critical finding and prove closure with rescans? (PCI DSS v4.0.1 Requirement 11.3.1)
3. Can you evidence tool currency, personnel qualifications, and independence? (PCI DSS v4.0.1 Requirement 11.3.1)

Plain-English interpretation (what this really means)

• Scanning is not the control outcome. The outcome is that high-risk and critical vulnerabilities in scope are found, fixed, and verified as fixed via rescan. (PCI DSS v4.0.1 Requirement 11.3.1)
• Your “severity” must map to your organization’s risk ranking method. PCI DSS ties “high-risk” and “critical” to your vulnerability risk rankings. That means you need a documented method that is consistently applied to scanner findings and exceptions. (PCI DSS v4.0.1 Requirement 11.3.1)
• Independence is part of control design. The person/team running scans cannot be the same person/team solely responsible for the systems being scanned, without a defensible independence model (for example, a central security team scanning infrastructure owned by IT operations). (PCI DSS v4.0.1 Requirement 11.3.1)

Who it applies to

This applies to entities that store, process, or transmit account data, and service providers whose people, processes, or systems can affect the security of the cardholder data environment. (PCI DSS v4.0.1 Requirement 11.3.1)

Operational contexts where this shows up

• Merchants with segmented networks: you must scan the CDE and any connected systems that could impact it (for example, jump hosts, identity services, logging platforms) based on your PCI scope decisions. (PCI DSS v4.0.1)
• Service providers: internal scanning must cover multi-tenant management planes and supporting infrastructure that can impact customer CDEs, not only customer-facing card-processing nodes. (PCI DSS v4.0.1)
• Cloud and hybrid: scanning must still be internal to the environment; you may need a mix of host-based and network-based scanning to cover ephemeral assets, images, and container hosts, but the control obligations remain the same. (PCI DSS v4.0.1 Requirement 11.3.1)

What you actually need to do (step-by-step)

1) Define scope as an auditable list

• Produce an inventory of in-scope IP ranges, subnets, hostnames, and environments (prod and any other in-scope tiers).
• Tie each asset group to an owner and a business service.
• Record inclusions/exclusions and the rationale so scope is stable across quarters. (PCI DSS v4.0.1)

Deliverable: “Internal Vulnerability Scan Scope” document or CMDB export with a PCI scope tag.

2) Set your scan cadence and lock it into operations

• Create a recurring scan schedule that covers all in-scope asset groups at least once every three months. (PCI DSS v4.0.1 Requirement 11.3.1)
• Define what constitutes “completion” (scan executed, results stored, triage performed).
• Build a backstop: if a scan fails (credentials invalid, host unreachable), require rerun and track as an exception until scanned.

Deliverable: Calendar/schedule artifact plus scanner configuration showing recurring jobs.

3) Standardize risk ranking for vulnerabilities

• Document your vulnerability risk ranking method and how scanner severities map to “high-risk” and “critical.” (PCI DSS v4.0.1 Requirement 11.3.1)
• Define how you adjust rankings for exploitability, asset criticality, and compensating controls, and who can approve downgrades.
• Make exceptions explicit: accepted risk requires documented approval and an expiration or review trigger.

Deliverable: Vulnerability Risk Ranking Standard (and an exception workflow).

4) Run scans with a current tool configuration

• Confirm the scanner is kept up to date with latest vulnerability information before each scan cycle (for example, signature/plugin feed updates). (PCI DSS v4.0.1 Requirement 11.3.1)
• Use authenticated scanning where feasible to reduce false negatives and improve patch verification.
• Confirm scanning coverage: network segments, OS families, and key middleware.

Deliverable: Evidence of update status + scan policy configuration snapshots.

5) Triage findings and drive remediation to closure

• Intake findings into a ticketing system with asset owner assignment.
• Identify all high-risk and critical items and track them to remediation. (PCI DSS v4.0.1 Requirement 11.3.1)
• Require remediation evidence in the ticket (patch record, configuration change, compensating control justification if applicable).

Deliverable: Tickets linked to scan findings with closure notes and change records.

6) Rescan to verify closure (this is where audits are won)

• Perform rescans that confirm all high-risk and critical vulnerabilities have been resolved. (PCI DSS v4.0.1 Requirement 11.3.1)
• Treat “verified fixed” as a separate status from “remediated.”
• If an item cannot be fixed quickly, document mitigation and an approved exception, but be careful: the requirement’s default expectation is resolution and verification for high/critical items. (PCI DSS v4.0.1 Requirement 11.3.1)

Deliverable: Rescan report(s) showing the specific vulnerabilities no longer present, with traceability to original findings.

7) Prove personnel qualification and tester independence

• Document who runs internal scans and why they are qualified personnel (training, certifications, experience, role description). (PCI DSS v4.0.1 Requirement 11.3.1)
• Document organizational independence of the tester (org chart, RACI, separation of duties statement, or management attestation). (PCI DSS v4.0.1 Requirement 11.3.1)

Deliverable: Role-based qualification evidence + independence memo.

Required evidence and artifacts to retain

Use this as your audit evidence checklist:

• Quarterly internal scan reports for each in-scope environment, with timestamps and scope details. (PCI DSS v4.0.1 Requirement 11.3.1)
• Proof the scanner is current (update logs, screenshots, or system status exports). (PCI DSS v4.0.1 Requirement 11.3.1)
• Vulnerability risk ranking methodology, including the definition of “high-risk” and “critical.” (PCI DSS v4.0.1 Requirement 11.3.1)
• Remediation tickets mapped to scan findings, including approvals and change records. (PCI DSS v4.0.1 Requirement 11.3.1)
• Rescan reports proving closure of high/critical findings. (PCI DSS v4.0.1 Requirement 11.3.1)
• Tester qualification and independence evidence (training records, org chart, SoD/RACI). (PCI DSS v4.0.1 Requirement 11.3.1)

Daydream tip (practical): Many teams lose time assembling traceability across scanner → ticketing → change management → rescan proof. Daydream can act as the control evidence layer by linking scan outputs to remediation artifacts and preserving a quarter-by-quarter audit packet without manual chasing.

Common exam/audit questions and hangups

Expect these questions from a QSA or internal audit:

• “Show me the last four quarters of internal scans for the entire in-scope environment.” (PCI DSS v4.0.1 Requirement 11.3.1)
• “How do you define high-risk and critical, and who approves severity overrides?” (PCI DSS v4.0.1 Requirement 11.3.1)
• “Pick one high finding from last quarter. Show the ticket, the fix, and the rescan proof.” (PCI DSS v4.0.1 Requirement 11.3.1)
• “How do you know the scanner plugins/signatures were current at scan time?” (PCI DSS v4.0.1 Requirement 11.3.1)
• “Who runs scans, and how are they independent from system owners?” (PCI DSS v4.0.1 Requirement 11.3.1)

Hangups that slow audits:

• Scope drift (assets appear in one quarter but not the next without explanation).
• “Closed” tickets without rescan verification.
• Independence asserted verbally but not documented.

Frequent implementation mistakes (and how to avoid them)

1. Scanning only the CDE subnet, ignoring connected systems
   Fix: maintain a scoped asset inventory that includes systems that can impact CDE security, and keep it consistent across quarters. (PCI DSS v4.0.1)

2. Treating scanner severity as final severity
   Fix: document your risk ranking method and apply it consistently; require approval for overrides and retain the rationale. (PCI DSS v4.0.1 Requirement 11.3.1)

3. No clean linkage from finding → fix → rescan
   Fix: enforce ticket templates that require a finding ID, remediation evidence, and a rescan attachment before closure. (PCI DSS v4.0.1 Requirement 11.3.1)

4. Scanner is “installed,” but feeds are stale
   Fix: make scanner update status a pre-flight check and capture evidence each cycle. (PCI DSS v4.0.1 Requirement 11.3.1)

5. Independence is unclear in small teams
   Fix: document compensating governance: separation via management review, second-person validation, or central security ownership of scanning with IT owning remediation. Keep the memo and org chart ready. (PCI DSS v4.0.1 Requirement 11.3.1)

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so this page does not cite specific actions. Practically, internal scanning failures create two compounding risks: exploitable weaknesses persist in production, and you cannot produce remediation-and-rescan evidence during PCI scoping and assessor testing. (PCI DSS v4.0.1 Requirement 11.3.1)

A practical 30/60/90-day execution plan

30 days (Immediate stabilization)

• Confirm in-scope asset inventory and scanning coverage expectations for the CDE and connected systems. (PCI DSS v4.0.1)
• Write or refresh the vulnerability risk ranking method and approval rules. (PCI DSS v4.0.1 Requirement 11.3.1)
• Assign roles: scan operator, remediation owners, approver for exceptions, and independent reviewer. (PCI DSS v4.0.1 Requirement 11.3.1)

60 days (Operationalize the workflow)

• Implement recurring scan jobs for all in-scope asset groups and capture scanner update evidence each cycle. (PCI DSS v4.0.1 Requirement 11.3.1)
• Implement ticketing intake with required fields for traceability and remediation evidence.
• Run a full scan, triage, and start remediation for high/critical findings with a rescan gate. (PCI DSS v4.0.1 Requirement 11.3.1)

90 days (Make it audit-ready)

• Complete remediation and rescans for all high/critical items from the cycle and compile an audit packet. (PCI DSS v4.0.1 Requirement 11.3.1)
• Perform a mock audit: sample findings and walk them end-to-end (finding → ticket → change → rescan).
• Formalize independence and qualification documentation and store it with the quarterly scan evidence. (PCI DSS v4.0.1 Requirement 11.3.1)

Frequently Asked Questions

Do internal vulnerability scans have to be quarterly, or can we scan more often?

The requirement sets a minimum of at least once every three months; scanning more often is fine if you still retain evidence and close high/critical findings with rescans. (PCI DSS v4.0.1 Requirement 11.3.1)

What counts as “internal” for cloud environments?

“Internal” is about scanning from within the environment boundary or with internal visibility into in-scope systems. Keep scope definitions consistent and ensure the scans cover the systems that impact the CDE. (PCI DSS v4.0.1 Requirement 11.3.1)

Can we close a high finding after patching without a rescan?

No. The requirement expects rescans that confirm all high-risk and critical vulnerabilities have been resolved, so closure needs verification evidence. (PCI DSS v4.0.1 Requirement 11.3.1)

Who is considered “qualified personnel” to run internal scans?

PCI DSS requires scans be performed by qualified personnel, so you should document training, experience, and role responsibilities for the scan operator(s). Keep that documentation with the scan evidence. (PCI DSS v4.0.1 Requirement 11.3.1)

How do we show “organizational independence” if the security team reports to the CIO?

Independence is typically demonstrated through separation of duties and governance, not necessarily a separate executive. Document who runs scans, who owns remediation, and who provides independent review or oversight. (PCI DSS v4.0.1 Requirement 11.3.1)

What evidence is most likely to fail an audit for this requirement?

The common failure is missing traceability: you have scan reports, but you cannot prove high/critical items were fixed and verified by rescan. Build a repeatable audit packet per quarter that ties findings to tickets and rescans. (PCI DSS v4.0.1 Requirement 11.3.1)