Your PSD2 compliance certification arrived. The SCA (Strong Customer Authentication) tests passed. The API gateway logs show clean traffic. Your board sees a green tick. Your CISO breathes out. The regulator is satisfied. But the real-world threat surface for open banking in the UK has shifted dramatically since the FCA first enforced the Payment Services Regulations 2017. Three critical security gaps now sit quietly inside the compliance boundaries your last audit blessed. Missing them costs more than a regulatory fine — it erodes the trust that makes open banking work.
Our team at Pyralink Innovation Ltd has conducted enough post-compliance penetration tests to know the pattern. A bank or third-party provider (TPP) clears the PSD2 SCA requirements — dynamic linking, multi-factor authentication, transaction risk analysis — and assumes the job is done. Meanwhile, attackers target the seams between compliance and operational reality. Token replay attacks on payment initiation APIs. Privilege escalation through misconfigured consent dashboards. Data leakage via the very sandbox environments regulators require. These are not hypothetical. They are production incidents we have helped clients remediate in 2025 and early 2026.
This post names three specific gaps your PSD2 compliance review almost certainly missed. For each one, we explain the operational risk, the UK regulatory context, and exactly what to fix. The advice is actionable today. No fluff. No future-gazing. Just the gaps that keep our consultants awake at night.
Gap One: Payment API Security — The Token Lifecycle Blind Spot
PSD2 mandates Strong Customer Authentication at the point of payment initiation. That is the transaction moment. Your SCA checks are robust. Your one-time passwords and biometrics work. But the payment API security framework around token management often gets a fraction of the attention. Access tokens for TPPs, refresh tokens, and consent tokens — each has a lifecycle that extends far beyond the authentication event.
The UK Finance authority and the FCA have both issued guidance on secure token handling for open banking APIs, but compliance reviews rarely dig into token expiration policies at the infrastructure layer. We have seen tokens issued with lifetime windows of 90 days in production. That is an eternity in an API ecosystem. If a token is stolen or leaked during that window — via a compromised TPP system, a logging vulnerability, or a misconfigured cloud bucket — an attacker can replay it to initiate payments without any SCA requirement. The token itself bypasses the authentication entirely.
The fix is not complex, but it demands precision. Enforce token expiration not just at the application layer but at the API gateway and database level. Implement token revocation lists that propagate in real time. Audit every token issue against the consent record — if the user revoked consent 72 hours ago but the token is still valid, your API is exposed. We recommend a maximum token lifetime of 15 minutes for access tokens in production. Refreshes should re-authenticate via SCA, not silently renew. This logic belongs in your API gateway configuration, not in application code that changes in every sprint.
For institutions managing multiple API endpoints, a unified auditing tool like our CloudAuditX platform can map token lifecycles across payment initiation, account information, and confirmation-of-funds APIs. It surfaces exactly where token policies deviate from the principle of least privilege — a finding your PSD2 compliance review likely missed because the reviewer checked the SCA flow, not the token warehouse.
Gap Two: Consent Dashboard Misconfiguration — The Privilege Escalation Vector
PSD2 requires explicit consent from the payment service user. The consent dashboard — where users grant, review, and revoke permissions — is the user-facing embodiment of that requirement. But compliance reviews treat the dashboard as a UI feature, not a security boundary. That is a mistake.
In 2025, our team assessed a major UK open banking provider where the consent revocation API endpoint was accessible without proper authorisation checks. A logged-in user could send a crafted PUT request to revoke another user's consent. Worse, the dashboard's "view consents" endpoint returned the full consent record, including the TPP's internal API keys, for any authenticated user. The PSD2 compliance review had passed because the SCA flow and consent capture screens worked correctly. The backend API that powered that dashboard had never been penetration tested as a separate surface.
This is a privilege escalation risk with direct financial consequences. If an attacker gains access to a standard user account — say, through a credential stuffing attack on the bank's retail portal — they can navigate the consent dashboard to escalate privileges. They delete legitimate consents to disrupt service. They view TPP credentials to enable lateral movement into partner systems. They grant themselves access to third-party accounts. The consent dashboard becomes an attack surface, not a control.
We advise treating the consent dashboard as a privileged administrative interface, even if it appears user-facing. Apply role-based access controls (RBAC) that distinguish between "consent owner" and "consent viewer." Implement idempotent revocation that requires the user's session to match the consent owner's identity at the session level, not just the token level. Audit all dashboard API calls for privilege escalation attempts — using parameter tampering, HTTP method swapping, or forced browsing. If your PSD2 review did not include a dedicated API abuse test against the consent dashboard, schedule one this quarter.
Our fractional vCISO service regularly identifies these gaps during architecture reviews that go beyond standard compliance checklists. A vCISO who has seen nine different open banking implementations knows exactly where the dashboards break.
Gap Three: Sandbox Environment Data Leakage — The Compliance Loophole
PSD2 requires that TPPs access production-like sandbox environments for testing. This is a regulatory necessity — TPPs need to validate their integrations. But sandboxes are often built with production data patterns, or they use synthesised data that still reveals internal schema structures. The compliance reviewer checks that the sandbox exists and that TPPs have access. They rarely check what the sandbox exposes about the production infrastructure.
In one engagement, our consultants found a sandbox environment for an account information service provider (AISP) that mirrored the production database schema exactly — including the names of internal tables, stored procedures, and error handling routines. A TPP developer, or a malicious actor impersonating a TPP, could reverse-engineer the production API surface from the sandbox error messages alone. The PSD2 compliance review had given the sandbox a clean pass because it did not contain real customer data. It missed the information disclosure risk entirely.
Sandboxes must be security-tested as independent environments, not just function-tested for API specifications. Strip them of any database schema that matches production. Use randomised schema names. Ensure error messages return generic text — no internal stack traces, no table names, no hint of SQL structure. Apply rate-limiting and API key controls to sandboxes that mirror production precisely. If a TPP's API key for the sandbox is compromised, the attacker should gain nothing more than a working example of a generic payment flow with no bearing on the production system.
And here is the regulatory angle that firms miss: the UK's NIS Regulations 2018, enforced by the ICO and sector regulators, require operators of essential services — including payment infrastructure — to protect the "confidentiality, integrity, and availability" of their systems. A sandbox that leaks schema information violates the confidentiality principle. It is a reportable gap under NIS. Your PSD2 compliance review did not assess NIS compliance. It should have.
For a complete view of your regulatory posture across PSD2, NIS Regulations, and UK GDPR, our free compliance scanner maps your current controls against the frameworks that actually apply to UK financial services. It is a starting point for the gaps your PSD2 review left open.
How Pyralink Innovation Ltd Closes These Gaps
We are not auditors who tick boxes. We are implementers who understand production. Pyralink Innovation Ltd, led by Michael Adedeji (CISM, CISA, CC, MSc Data Science), delivers security that matches the speed of open banking. Our team holds £5 million professional indemnity insurance and has executed penetration tests, architecture reviews, and compliance remediation for UK payment institutions, AISPs, PISPs, and account-servicing payment service providers (ASPSPs).
Our approach is direct: identify the gap, show the exploit path, implement the fix. We do not produce 200-page reports that gather dust on a compliance shelf. We produce a remediation timeline and validated controls. For token lifecycle issues, we reconfigure your API gateway with partner teams. For consent dashboard vulnerabilities, we run API abuse tests and harden the endpoints. For sandbox leakage, we redesign the environment to decouple it from production schemas.
We also provide the frameworks to sustain that security over time. Our ISO 27001 certification support integrates open banking-specific controls into your ISMS — because PSD2 compliance is not a one-time achievement. It is a continuous obligation.
If you hold an active PSD2 compliance certificate but have not tested your token lifecycle, consent dashboard, or sandbox environment in the last six months, your security posture has a known blind spot. We can close it in a sprint. Two weeks, three consultants, one focused engagement. The cost of the remediation is a fraction of what a single token replay incident costs in regulatory fines, compensation, and reputational damage.
Your Next Steps — Immediate Actions for Your Security Team
- Audit token expiration policies. Pull every API gateway log for access tokens over 15 minutes old. If any exist beyond 15 minutes, flag them for revocation and policy change.
- Penetration test the consent dashboard API. Run an automated API abuse scanner against all endpoints — not just the UI — looking for privilege escalation, parameter tampering, and forced browsing vulnerabilities.
- Isolate sandbox environments. Compare sandbox database schemas to production. Strip any internal naming conventions, error messages, or API structures that do not appear in the public specification.
- Integrate NIS compliance into your PSD2 controls. An attack on payment API security that compromises confidentiality is a NIS incident. Ensure your incident response plan covers both frameworks.
- Run a free scan. Use our free CloudAuditX scan to map your current controls against the UK-specific regulatory stack.
Your next compliance review will ask harder questions. Be prepared to answer them — not with certificates, but with verified security posture. Book a free security review with our team to close the gaps before they close your operation.