Severity: CriticalVulnerabilityPrompt injection
X402 SDK Default Configuration Permits Unrestricted Token Spending by AI Agents
Global
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An x402 SDK default configuration allowed AI agents to sign unbounded payment authorizations to malicious APIs, risking depletion of their entire token balances. The vulnerability affected agents with automatic payment signing and no spending caps, until patches introduced spending limits in August 2026. The flaw exposed agents to full financial loss if they interacted with compromised or adversarial payment endpoints.
What to do
Apply x402 SDK patches released August 18 and audit agent payment signing policies to enforce explicit spending limits.
Mapped framework pillars
Sources
#AI agents#token security#SDK vulnerability#payment authorization#financial loss#x402