A hostile API could have asked an auto-signing agent for the whole wallet
Security firm V12 published a review of the x402 payment SDK on October 22, 2026, after reporting it to the project on August 12. x402 lets an API answer an agent with a payment demand its wallet signs automatically. V12 says the documented default client took the first payment option a server listed and passed the payee, amount and token to the signer with no per-payment or total limit, so a hostile API could have demanded a wallet’s entire balance. Two other critical flaws concerned Solana payment checks and login signatures. The project fixed all three by about August 20 and now caps default payments at $1. V12 says its tests were local, no funds moved and no attacks are known. How many deployments ran the unprotected default is unknown.
Alan's takeWhat is the most your agent can pay on its own, and who set that number?