---
id: CVE-2026-87119
title: >-
  Authentication Bypass by Capture-replay in ZenHive mpp allows an attacker
  holding a captured subscription activation credential to charge the payer
  repeatedly.


  The payer signs a Tempo KeyAuthorization over the chain id, key type, key id…
summary: >-
  Authentication Bypass by Capture-replay in ZenHive mpp allows an attacker
  holding a captured subscription activation credential to charge the payer
  repeatedly.


  The payer signs a Tempo KeyAuthorization over the chain id, key type, key id…
severity: high
cvss: 8.2
cvssVector: 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'
cwe:
  - CWE-294
vendor: ZenHive
product: mpp
affected:
  - mpp >= 0.14.0 < 0.16.2
  - >-
    zenhive/mpp >= db464dfa9a86ccda58f0827101f6da6bd8aafa78 <
    4b6eaec02af0e8485cfb4ff68f467d075ed5dd6f
published: '2026-09-22'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T19:09:32.273'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-87119'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-87119.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ZenHive/mpp/commit/4b6eaec02af0e8485cfb4ff68f467d075ed5dd6f
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ZenHive/mpp/commit/db464dfa9a86ccda58f0827101f6da6bd8aafa78
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://github.com/ZenHive/mpp/security/advisories/GHSA-p9fv-9w58-95x2'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-87119'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-22T12:02:12.184296Z'
cvssSource: cna
ingestedAt: '2026-09-22T12:03:01.595Z'
epss: 0.00574
epssPercentile: 0.45008
---

## Overview

Authentication Bypass by Capture-replay in ZenHive mpp allows an attacker holding a captured subscription activation credential to charge the payer repeatedly.

The payer signs a Tempo KeyAuthorization over the chain id, key type, key id, expiry, limits and scopes only, with nothing tying it to the challenge that prompted it. MPP.Methods.Tempo.KeyAuthorization.verify/3 in lib/mpp/methods/tempo/key_authorization.ex pins each of those signed fields against the subscription request, and the access key it pins is a static per-endpoint server key, so one signed authorization verifies against every challenge the server issues for the same subscription terms. MPP.Methods.Tempo.Subscription.activate/4 deduplicates activations by challenge id, so presenting the captured credential under a fresh challenge produces a different dedup key, claim_activation succeeds, and the subscription transaction is built and broadcast again. Each replay charges the payer's wallet a new first-period settlement and re-authorizes the server key, bounded only by the subscription expiry and the chain's own semantics for re-installing an existing key.

This issue affects mpp: from 0.14.0 before 0.16.2.

## Remediation

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