When the mpp Elixir library is configured as fee payer (fee_payer: true), MPP.Tempo.Transaction.cosign_fee_payer/3 re-signs the client-supplied base fields of the 0x76 AASigned envelope verbatim, including max_fee_per_gas and max_priority_fee_per_gas, without validating that they are within reasonable bounds. A malicious client embeds arbitrarily large values for these fields in the signed envelope. The server co-signs and broadcasts the transaction. The effective_gas_price billed against the fee-payer wallet is derived from the attacker-supplied ceilings, so the server pays those inflated per-gas rates out of its own wallet. A single crafted request can drain the wallet entirely, after which the server can no longer sponsor gas for legitimate payment requests.
This issue affects mpp: from 0.2.0 before 0.6.0.
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
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Fri, 17 Jul 2026 13:30:00 +0000
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ssvc
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Fri, 17 Jul 2026 10:30:00 +0000
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| Description | Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to drain the fee-payer wallet in a single request by naming an arbitrarily high gas price. When the mpp Elixir library is configured as fee payer (fee_payer: true), MPP.Tempo.Transaction.cosign_fee_payer/3 re-signs the client-supplied base fields of the 0x76 AASigned envelope verbatim, including max_fee_per_gas and max_priority_fee_per_gas, without validating that they are within reasonable bounds. A malicious client embeds arbitrarily large values for these fields in the signed envelope. The server co-signs and broadcasts the transaction. The effective_gas_price billed against the fee-payer wallet is derived from the attacker-supplied ceilings, so the server pays those inflated per-gas rates out of its own wallet. A single crafted request can drain the wallet entirely, after which the server can no longer sponsor gas for legitimate payment requests. This issue affects mpp: from 0.2.0 before 0.6.0. | |
| Title | Unbounded max_fee_per_gas in mpp Tempo fee-payer enables single-request wallet drain | |
| First Time appeared |
Zenhive
Zenhive mpp |
|
| Weaknesses | CWE-1284 | |
| CPEs | cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Zenhive
Zenhive mpp |
|
| References |
| |
| Metrics |
cvssV4_0
|
Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-07-17T12:53:17.645Z
Reserved: 2026-07-06T14:05:47.003Z
Link: CVE-2026-59695
Updated: 2026-07-17T12:52:53.192Z
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