CVE-2026-59252
HighCVSS 8.2Exploitation Probability (EPSS)
Low risk29th percentile - higher than 29% of all known CVEs
Summary
A vulnerability in the mpp library (ZenHive) allows an unauthenticated remote client to drain the fee-payer wallet by submitting EVM transactions with a deliberately low gas limit. The server co-signs and broadcasts the transaction, which fails due to out-of-gas, but the fee-payer wallet is charged for the burned gas while the attacker pays nothing. This leads to denial of service for legitimate clients as the fee-payer wallet runs out of funds.
Risk Assessment
The organization risks depletion of the fee-payer wallet, preventing gas sponsorship for legitimate transactions and causing service disruption. The attack can be repeated at minimal cost to the attacker.
Recommendation
Immediately update the mpp library to version 0.6.0 or later, which includes a fix for gas limit validation. Until the update is applied, temporarily disable the fee_payer feature or manually validate the gas limit in client transactions.
Other vulnerabilities in mpp
See all- CVE-2026-59695High
A vulnerability in the ZenHive mpp library allows an unauthenticated remote attacker to drain the fee-payer wallet in a single request by specifying an arbitrarily high gas price. The library does not validate the max_fee_per_gas and max_priority_fee_per_gas fields before co-signing the transaction, causing the server's wallet to be charged inflated costs.
- CVE-2026-59694High
A vulnerability in the mpp library (ZenHive) allows an unauthenticated remote client to inflate the fee-payer's gas cost by adding a large number of fabricated EIP-2930 access list entries. The server co-signs the transaction without validating the list length or contents, leading to a multiple increase in gas costs.
Original NVD description (English source)
Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to drain the fee-payer wallet, resulting in denial of service for legitimate clients. When the mpp Elixir library is configured as fee payer (fee_payer: true), the MPP.Methods.Tempo payment method co-signs and broadcasts a client-supplied EVM transaction without first validating that the client-supplied gas_limit is sufficient to complete the intended call. A malicious client can submit a signed transferWithMemo transaction with gas_limit deliberately set just below the amount required for successful execution. The server co-signs the transaction and broadcasts it via rpc_broadcast_sync. The transaction runs out of gas during EVM execution and reverts, but the fee-payer wallet is still charged for the burned gas while the client pays nothing and receives no resource. Repeated requests from one or more malicious clients drain the fee-payer wallet at near-zero cost to the attacker, ultimately preventing the server from sponsoring gas for legitimate payment requests. The wait_for_confirmation = false (optimistic) path is also affected: it invokes simulate_payment_call via eth_call, but that simulation omits the gas parameter and therefore does not catch out-of-gas conditions. This issue affects mpp: from 0.2.0 before 0.6.0.