mppx: Gas Draining with padding

Details When the server acts as the feepayer, mppx 0.6.27 validates calldata using viem's decodeFunctionData, which is lenient about trailing bytes. The FeePayerPolicy caps gaslimit ≤ 2 M and maxfeepergas ≤ 100 Gwei but does not check calldata length. Tempo uses legacy calldata gas pricing: 16 ga...

CVE-2026-63627 mppx: Gas Draining with padding

mppx is a TypeScript interface for machine payments protocol. Prior to 0.8.2, FeePayerPolicy in src/tempo/internal/fee-payer.ts used decodeFunctionData to validate fee-sponsored calldata but did not reject trailing bytes. A client could append nonzero padding that increased intrinsic calldata gas...