Agentic Payment Security Audit
A fixed-scope security audit for x402, MPP and agent-wallet payment flows. We test replay, settlement races, cache leaks and spend controls before real money moves.
You might be experiencing...
Why Agentic Payments Need Their Own Audit
A normal web pentest checks logins, sessions and injection bugs. Agent payments add a different kind of risk. Money moves automatically, in milliseconds, with no chargebacks, triggered by software that can retry, run in parallel and be tricked.
The vulnerabilities researchers keep finding are mostly in the details: the SDK you picked, the order your server does things in, the CDN in front of it, and the wallet your agent signs with. Our agentic payment security audit tests exactly those parts.
What We Test
- Replay and idempotency: can one payment unlock a resource twice, or two hundred times?
- Settlement timing: do you release the resource before the payment is final?
- Settlement preemption: can someone settle your customer’s authorization before you do?
- Header and cache handling: can a proxy serve a paid response to someone who never paid?
- Mandate and token validation: are AP2 mandates and ACP or MPP tokens checked properly?
- Spend controls: can an agent be pushed past its budget, rate limit or allowlist?
- Key management: where agent keys live, who can use them, and how you rotate them
Who It Is For
- Startups launching x402 or MPP endpoints, agent wallets or agent-facing APIs, before a raise or an enterprise deal
- Fintechs and banks in the GCC adding agent payments and needing evidence for VARA, DIFC or ADGM
- Platforms that let third-party agents pay, where one weak integration exposes everyone
Want to understand the risks first? Read our agentic payment security guide or the security section of our x402 protocol guide.
Engagement Phases
Scoping
We map your payment flows (x402, MPP, AP2, ACP or custom), wallets, facilitators and the infrastructure in between, and agree what is in scope.
Protocol and implementation testing
We test replay and idempotency, settlement timing, settlement preemption, header and cache handling, and mandate or token validation against your staging environment.
Wallet and spend-control review
We review key management, per-agent budgets, rate limits, allowlists and approval thresholds, and try to get an agent to spend more than it should.
Report and retest
You get findings ranked by real-world impact with fixes your engineers can apply, and we retest once the fixes land.
Deliverables
Before & After
| Metric | Before | After |
|---|---|---|
| Replay protection | Assumed | Tested under retries and parallel requests |
| Paid-response caching | Unknown | Verified at CDN, proxy and app layers |
| Agent spend limits | Config value | Enforced before signing, tested |
| Evidence for buyers | None | Shareable audit summary |
Tools We Use
Frequently Asked Questions
What does an agentic payment security audit cover?
The payment flow end to end: the 402 challenge and response, payment signing, facilitator verification and settlement, how your servers and CDN handle paid responses, and the wallets and spending limits your agents use. We cover x402, MPP, AP2, ACP and custom flows.
Why audit x402 specifically?
Because implementations get it wrong. A May 2026 study found 11 vulnerabilities across three open-source x402 SDKs and four live endpoints, including an endpoint that granted 248 resources for one payment and another that served paid responses from cache. There are no chargebacks on stablecoin rails, so prevention is the only control.
How long does the audit take?
Most audits take 3 to 4 weeks from scoping to final report, including a retest of the fixes. A single-endpoint review can be faster.
Do you need production access?
No. We test against staging or testnet deployments wherever possible. For production-only configuration such as CDN rules, we review the configuration rather than attack live traffic.
Is this useful for VARA or ADGM licensing?
Yes. Regulators in the UAE expect evidence of security testing and controls over digital-asset flows. The audit report and summary can support that evidence, and we work alongside our regulatory compliance service for the licensing itself.
Complementary Services
Get Started for Free
Schedule a free consultation with our payment infrastructure team. 30-minute call, actionable results in days.
Every engagement is scoped by our principal architect, Adrian Vale: 20+ years in production engineering, 40+ professional certifications. Meet Adrian
Talk to an Expert