Jan Curn: x402 Not Ready for Prime Time—Double-Spend and Protocol Wars Threaten Crypto Payments' Window of Opportunity

At a recent industry symposium, payment protocol expert Jan Curn publicly stated that x402—a machine payment protocol based on HTTP 402—is currently unsuitable for agentic payments. He pointed out that the protocol has flaws in double-spend prevention and settlement finality, which could expose AI agents to financial losses in automated transactions. Curn argued that unless these issues are resolved, crypto payments will miss the critical window of opportunity opened by the current AI agent boom.

Curn also warned that the battle over standards for agentic payments is escalating into a "protocol war." Solutions like x402 and MCP (Model Context Protocol) are each going their own way, lacking a unified security and compliance framework, which leaves enterprises facing fragmentation risks when integrating. He urged the industry to strike a balance between speed of advancement and infrastructure robustness, warning that failure to do so could repeat the early DeFi setbacks caused by security vulnerabilities.

Based on his observations, most agentic payments remain in the testing phase, with limited real-money use cases. He emphasized that until mechanisms such as mandates, per-transaction limits, and pre-settlement screening mature, x402 should not be used for high-value transactions.