Improper Input Validation in ZenHive mpp Affects Resource Payment Handling
CVE-2026-89420

7.1HIGH

Key Information:

Vendor

Zenhive

Status
Mpp
Vendor
CVE Published:
22 September 2026

What is CVE-2026-89420?

The vulnerability in ZenHive's mpp product stems from improper validation of input quantity, specifically within the payment processing mechanism. When a client holds an open payment channel, they can exploit this flaw to acquire paid resources without incurring charges. The issue arises in the MPP.Session.Actions.accept_voucher function, which mistakenly treats vouchers that match the already-accepted cumulative amount as successful transactions. As a result, the system fails to correctly process the voucher, allowing repeated use of the same signed voucher under new challenges, leading to potential financial losses. This vulnerability affects versions from 0.14.0 up to 0.16.2.

Affected Version(s)

mpp 0.14.0 < 0.16.2

mpp 82df569c898be1137189e3648e1edb4af6363651 < 7270edc1dcfb58250cc5ee812876609206564165

References

https://github.com/ZenHive/mpp/security/advisories/GHSA-8...
relatedvendor-advisory
https://cna.erlef.org/cves/CVE-2026-89420.html
related
https://osv.dev/vulnerability/EEF-CVE-2026-89420
related

CVSS V4

Score:
7.1
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

E.FU
E.FU
Jonatan Männchen / EEF
.