Woofun AI reports that a comprehensive security audit has uncovered 31 previously unknown vulnerabilities within the infrastructure supporting x402, an HTTP-native standard designed for programmatic payments. The scope of this exposure is critical, as the 15 major facilitators analyzed in the study accounted for 99% of all observed transactions during the monitoring window. Each of these facilitators failed to adhere to at least one of eight essential rules governing payment verification or settlement, creating a systemic risk across the majority of the network's activity.

Structurally, facilitators serve as the shared middle layer in the x402 ecosystem, responsible for checking a client's signed payment proof, constructing and broadcasting the settlement, and frequently sponsoring network fees. Merchants rely on the response from these intermediaries to determine when to release protected services.

However, this dependency introduces significant attack vectors. A free-shopping attack occurs when a merchant releases a service before a clean, unique payment has fully settled. Asset theft provides an attacker with a route to value controlled by the facilitator. Service denial jams the payment lane with failing or resource-hungry settlements, while gas abuse forces the facilitator to pay the attacker’s execution bill.

The deeper driver of these risks is the lack of strict enforcement of ERC-6492 standards and settlement finality checks.

Woofun AI data shows that researchers successfully validated two free-shopping cases end to end, demonstrating the practical feasibility of these exploits. They classified 10 additional instances as high risk because actual financial loss depended on a merchant releasing service after verification without waiting for settlement or rolling back a failure. The study also identified three gas-abuse instances and one ERC-6492 asset-theft path. In a controlled proof of concept, the team induced a token approval but made no subsequent transfer and stole no funds, highlighting the potential for exploitation without immediate capital loss.

Notably, more than 93% of server addresses in the study were associated exclusively with one facilitator, indicating a high concentration of risk.

All 15 facilitators exhibited high-risk service-denial or cost-amplification paths, although the researchers did not run a gas-drain experiment or an availability-degrading load test to demonstrate a full outage. A separate address-based analysis covered more than 119 million Base and Solana transactions, estimating approximately $202,000 in gas and fees from Oct. 1 to Dec. 26, 2025. Within this volume, about $5,800 was associated with reverts, illustrating the tangible cost of failed transactions. This data underscores the financial inefficiency and vulnerability inherent in the current facilitator models, where uneconomic payments can still incur significant network costs.

The disclosure timeline reveals a mixed response from the industry. The researchers disclosed their findings to 14 of the 15 affected parties in January. As of Feb. 6, Coinbase, PayAI, and Mogami had collectively acknowledged six vulnerabilities. While some issues were fixed, others remained in progress. Because the results are anonymized, the paper does not identify which specific fix belonged to each vendor, leaving the broader market uncertain about the remediation status of individual providers. This lack of transparency complicates the ability of merchants to assess the security posture of their chosen facilitators.

Before merchants rely on x402 at greater scale, the authors recommend binding verification to settlement, reserving nonces, and rechecking time and account state. Strictly allowlisting ERC-1271 and ERC-6492 transaction shapes, capping sponsored fees, and rejecting uneconomic or non-settleable payments are also critical measures. Merchants should release service only after settlement succeeds or implement explicit rollback mechanisms. An open protocol still needs hard controls around the intermediary that decides what counts as paid and safe to execute. This marks a pivotal moment for the adoption of programmatic payments, where security must precede scalability.