Vulnerability in Zenhive Machine Payments Protocol
CVE-2026-67581
Authentication Bypass by Capture-replay in ZenHive mpp allows an unauthenticated remote client to obtain paid resources by resubmitting one settled on-chain transfer. MPP.Methods.EVM.verify/2 accepts a transaction-hash credential and matches a transfer purely on token, to and amount (ERC-20) or to and value (native). It binds the proof neither to the challenge being verified nor to any record of prior use, and the generic MPP.Plug dedup store keys on challenge.id, which is regenerated for every 402 response. On a static-price route, a single historical transfer matching the charge therefore satisfies an unbounded number of later charges, including transfers an attacker can read off a public block explorer. This issue affects mpp: from 0.3.0 before 0.6.3.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.006 (46.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 46.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
Weakness classification (CWE)
References
- 6b3ad84c-e1a6-4bf7-a703-f496b71e49db (related, vendor-advisory, Vendor Advisory)
- 6b3ad84c-e1a6-4bf7-a703-f496b71e49db (related, Third Party Advisory)
- 6b3ad84c-e1a6-4bf7-a703-f496b71e49db (related, Third Party Advisory)
- 6b3ad84c-e1a6-4bf7-a703-f496b71e49db (Patch, patch)
Frequently asked questions
- What is CVE-2026-67581?
- CVE-2026-67581 is a high-severity vulnerability in Zenhive Machine Payments Protocol, classified under Authentication Bypass by Capture-replay. CVSS score: 7.5/10. Published 2026-08-19.
- How severe is CVE-2026-67581?
- High severity. CVSS v3 base score is 7.5 out of 10.