Threat
Critical x402 SDK Flaw Could Let Malicious APIs Drain AI Agents’ Token Balances
First reported thehackernews.com
Page published
Earliest dated coverage: 23 Oct 2026 · First observed: 23 Oct 2026 · Latest dated coverage: 23 Oct 2026
Coverage timeline
Single-source incident — one report is available.
Why it matters
AI agents using x402 for automatic API payments need patched SDKs and explicit spending limits to prevent malicious endpoints from draining their token balances.
The x402 SDKs’ default client lacked a spending limit, allowing malicious APIs to request an AI agent’s entire supported-token balance when payments were automatically signed and applications imposed no limits. V12 reported 25 flaws, including three critical issues that the x402 Foundation fixed in its August 18 releases.