40+ Marketplaces & Platforms targets assessed

Marketplace security assessments
for products with buyers, sellers, and privileged operator roles

Marketplace products have layered trust boundaries: buyers, sellers, operators, payouts, support tooling, and often API integrations. Small authorization mistakes can quickly become multi-party data or payment exposure.

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What we test in Marketplaces & Platforms

Role confusion between buyer, seller, and operator paths

Payout and balance manipulation flaws

IDOR on listings, transactions, and support workflows

Admin tooling exposure and privilege escalation

Messaging, upload, and moderation workflow abuse

Third-party integration and webhook trust issues

Marketplaces & Platforms-specific concerns

Multi-sided trust boundaries

Financial and payout workflow integrity

Support tooling privilege escalation

Cross-tenant or cross-role data exposure

How a Marketplaces & Platforms engagement runs

Marketplace testing is role-confusion testing at scale. We operate accounts as buyer, seller, and operator simultaneously and probe every boundary between them — a seller reading another seller's payouts, a support tool that quietly grants admin scope, a listing-edit endpoint that skips ownership checks. Payout and balance flows get the same scrutiny as checkout, since that is where a flaw becomes a direct transfer.

The report separates 'one user's data' findings from 'whole platform' findings, because on a multi-sided product the second category is the existential one — and it is what buyers and partners ask about first.

Regulatory and compliance context

Marketplaces inherit obligations from every side they connect: payment data touches PCI DSS scope, seller identity verification feeds KYC obligations, EU platforms face DAC7 seller-income reporting, and GDPR governs the messaging and transaction data flowing between parties. Payout flows are doubly sensitive — a flaw is both a theft vector and a licensing problem for the payments entity. Reports distinguish the exposure class (single-party, counterparty, platform-wide) because regulators and acquiring partners ask in exactly those terms.

What we typically find in Marketplaces & Platforms

Role-boundary failures are the recurring pattern: seller endpoints reachable with a buyer token, support tools whose impersonate action skips re-authorization, and payout methods editable without verifying ownership of the connected account. We regularly find listing and order IDORs that expose counterparty details — addresses, phone numbers, payout summaries — and refund endpoints callable by either side of a transaction. Webhook receivers for payment and shipping partners that never verify signatures let external events rewrite order state.

What the report includes

Every verified finding with a reproducible proof-of-concept: the exact request sequence, the role it ran under, and the data or action it reached.

Severity rated on impact in your sector — funds moved, records exposed, tenants crossed — not a generic CVSS guess.

Remediation guidance per finding, written for the team that will implement the fix, plus a re-test window to verify each patch.

An executive summary your leadership and security questionnaire reviewers can read without a security background.

Marketplaces & Platforms assessment FAQ

How do you test multi-role systems?

By provisioned test accounts at each role level — buyer, seller, moderator, operator — and by attempting every privileged action from every unprivileged context.