EUVD-2026-45159
GHSA-r4hx-mhrp-xf73
Severity by source
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Unauthenticated network access to a fee-payer deployment (PR:N, AV:N, AC:L); no confidentiality or data-integrity impact; sustained gas/wallet drain is a resource-exhaustion availability impact (A:H).
Primary rating from Vendor (EEF).
CVSS VectorVendor: EEF
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
3DescriptionCVE.org
Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to inflate the fee-payer's gas cost per payment by a large multiplier, degrading the sponsor's operating margin.
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 the EIP-2930 access list, without validating its length or contents. EIP-2930 access list entries incur intrinsic gas (~2,400 gas per address, plus 1,900 gas per storage key) charged before any opcode executes, regardless of whether the listed addresses are ever touched. A malicious client submits a valid transferWithMemo call alongside a large number of fabricated access-list entries. The server co-signs and broadcasts the transaction. The intended transfer executes normally, but the fee-payer wallet pays a large multiple of the expected gas cost with no corresponding on-chain work.
At the maintainer's default of 137 access-list entries (fitting within Bandit's 10,000-byte per-header-field limit) and 100 Gwei max_fee_per_gas, per-payment gas cost rises from ~51,287 to ~380,087 gas, a 7.4x multiplier. Sustained abuse destroys the sponsor's operating margin on low-cost payments and, over time, drains the fee-payer wallet.
This issue affects mpp: from 0.2.0 before 0.6.0.
AnalysisAI
Economic resource exhaustion in the ZenHive mpp Elixir library (versions 0.2.0 through 0.5.x) lets an unauthenticated remote client inflate a sponsoring fee-payer's gas cost per payment by roughly 7.4x, draining the sponsor wallet over sustained abuse. When deployed with fee_payer: true, MPP.Tempo.Transaction.cosign_fee_payer/3 re-signs client-supplied base fields of the 0x76 AASigned envelope verbatim - including an oversized EIP-2930 access list - without validating length or contents, so intrinsic gas is charged for fabricated entries that touch nothing on-chain. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the mpp server to be deployed as fee payer (fee_payer: true), invoking MPP.Tempo.Transaction.cosign_fee_payer/3 to sponsor gas for Tempo transactions on affected versions 0.2.0 through 0.5.x. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This is a credible but bounded financial-abuse risk rather than a system-compromise flaw. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A server operator runs mpp as a fee payer to sponsor gas for user payments. A malicious client submits a legitimate transferWithMemo call but pads the EIP-2930 access list with 137 fabricated address entries; the server co-signs and broadcasts it, and the transfer succeeds while the fee-payer wallet pays about 380,087 gas instead of ~51,287 (7.4x) at 100 Gwei. … |
| Remediation | Upgrade to mpp 0.6.0, which is the vendor-released patch (commit 5d6338e2334084c5f2a78cfcca474830733ed7e8) that adds MPP.Methods.Tempo.FeePayerPolicy to validate the client-signed 0x76 envelope's gas economics before co-signing - bounding gas_limit, max_fee_per_gas, max_priority_fee_per_gas, and the total-fee budget, and rejecting non-empty access lists; the fix is safe-by-default so existing fee_payer: true deployments are protected without config changes, and it also closes the related unbounded-fee vector GHSA-vv77-66rf-pm86. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, audit all systems running ZenHive mpp Elixir library versions 0.2.0 through 0.5.x to identify instances with fee_payer enabled, implement granular monitoring for transaction gas cost anomalies, and establish alerts for cost inflation. …
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Fee-payer wallet draining in ZenHive mpp (Elixir) 0.2.0-0.5.x lets an unauthenticated remote client empty the sponsor's
Wallet-draining denial of service in ZenHive mpp (Elixir library) versions 0.2.0 through 0.5.x affects deployments confi
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