---
id: CVE-2026-82750
title: >-
  Improper Validation of Specified Quantity in Input in ZenHive mpp allows an
  unauthenticated remote client to inflate the fee-payer's gas cost per
  sponsored payment by a large multiplier and to have the sponsor pay for
  EIP-7702 account de…
summary: >-
  Improper Validation of Specified Quantity in Input in ZenHive mpp allows an
  unauthenticated remote client to inflate the fee-payer's gas cost per
  sponsored payment by a large multiplier and to have the sponsor pay for
  EIP-7702 account de…
severity: high
cvss: 8.3
cvssVector: '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'
cwe:
  - CWE-1284
vendor: ZenHive
product: mpp
affected:
  - mpp >= 0.2.0 < 0.16.1
  - >-
    zenhive/mpp >= d29d54e507918db00a5b65d90136b73166c017d7 <
    0482572b47e1ffe1537ab80ab613d47b92833c2d
published: '2026-09-06'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T19:20:01.200'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-82750'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-82750.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ZenHive/mpp/commit/0482572b47e1ffe1537ab80ab613d47b92833c2d
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://github.com/ZenHive/mpp/security/advisories/GHSA-5qrp-r24c-w6jr'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-82750'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-08T18:25:27.116993Z'
cvssSource: cna
epss: 0.00524
epssPercentile: 0.42003
ingestedAt: '2026-09-07T06:06:09.643Z'
---

## Overview

Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to inflate the fee-payer's gas cost per sponsored payment by a large multiplier and to have the sponsor pay for EIP-7702 account delegations of the client's choosing.

When the server sponsors Tempo payments, MPP.Methods.Tempo.FeePayerPolicy.measure/3 in lib/mpp/methods/tempo/fee_payer_policy.ex bounds the gas fields, the fee budget, the validity window and the access list of the client-signed 0x76 envelope, but never reads its aa_authorization_list field. Every signed delegation in that list is charged as intrinsic gas before the payment call runs, so a client attaching delegations from throwaway authority keys makes the sponsor pay for them within the default gas_limit ceiling. At the reporter's default of seven entries the sponsored cost rises from about 46,575 gas to about 1,884,087 gas. Because each entry is applied as a persistent set-code delegation, a client can also upgrade its own accounts to delegated code at the sponsor's expense.

This issue affects mpp: from 0.2.0 before 0.16.1.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.