---
id: CVE-2026-73136
title: >-
  Authentication Bypass by Capture-replay in ZenHive mpp allows an
  unauthenticated third party to obtain paid resources by replaying a transfer
  settled by an unrelated payer.


  MPP.Methods.Tempo normally binds a settled TIP-20 TransferWithM…
summary: >-
  Authentication Bypass by Capture-replay in ZenHive mpp allows an
  unauthenticated third party to obtain paid resources by replaying a transfer
  settled by an unrelated payer.


  MPP.Methods.Tempo normally binds a settled TIP-20 TransferWithM…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'
cwe:
  - CWE-294
vendor: zenhive
product: machine_payments_protocol
affected:
  - 'machine_payments_protocol >= 0.6.1, < 0.6.4'
patched:
  - machine_payments_protocol 0.6.4
published: '2026-08-19'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T18:17:22.870'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73136'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-73136.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ZenHive/mpp/commit/2207d7f456ae14c1d3fcacc6f635bf4f8cee1a34
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://github.com/ZenHive/mpp/security/advisories/GHSA-34g7-vx6g-82mq'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-73136'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
epss: 0.00417
epssPercentile: 0.35684
ingestedAt: '2026-09-10T19:03:26.846Z'
---

## Overview

Authentication Bypass by Capture-replay in ZenHive mpp allows an unauthenticated third party to obtain paid resources by replaying a transfer settled by an unrelated payer.

MPP.Methods.Tempo normally binds a settled TIP-20 TransferWithMemo to the specific challenge under verification through an attribution nonce carried in the memo. When a static "memo" is configured in method_config, check_matched_memo_binding/3 returns the match unconditionally and that binding is skipped, leaving only token, recipient, amount and the static memo value to match on. The static memo is echoed in every unauthenticated 402 response and Tempo transfers are public, so an attacker can take any matching transfer paid by a legitimate customer, request a fresh challenge for the same route, and present that transaction hash as a type="hash" credential. The hash path performs no sender or signature check tying the presenter to the wallet that broadcast the transfer.

This issue affects mpp: from 0.6.1 before 0.6.4.

## Affected

- `machine_payments_protocol >= 0.6.1, < 0.6.4`

## Remediation

Upgrade past the affected range:

- `machine_payments_protocol 0.6.4`