AI
x402 SDK flaw could let malicious APIs drain AI agent balances
Oct 23, 2026 · Summarized by Fundy Tech from 3 sources
The 30-second version
V12 says a flaw in x402 SDKs could let a malicious API push an AI agent to sign away its full token balance. The foundation says the critical issues were fixed in August 18 releases.
Key points
- The missing spending limit affected the default client.
- Three critical flaws were fixed in August 18 releases.
- No public attacks have been reported.
Why it matters
If your software uses AI agents that can sign payments, a bad API could empty a wallet or trigger unwanted transactions. Households and small businesses using automated AI tools should review spending controls before letting agents pay for services.
Who’s affected: AI agents using x402 SDKs for payments
What to do
- Update x402 SDKs to the August 18 releases or later.
- Set spending limits and payment policies.
- Review any agent that can sign transactions automatically.
Original reporting
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