On-chain transfer proof is not single-use in mpp EVM payment method, enabling cross-challenge replay (CVE-2026-67581) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-67581

On-chain transfer proof is not single-use in mpp EVM payment method, enabling cross-challenge replay

Answer in brief

CVE-2026-67581 records a Unknown severity vulnerability in On-chain transfer proof is not single-use in mpp EVM payment method, enabling cross-challenge replay. The current sources do not mark it as known exploited. The current feed maps ZenHive/mpp (generic), ZenHive/mpp (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 19, 2026Updated Aug 19, 2026Source checked Aug 19, 2026First seen by HOL Aug 19, 2026Material review Aug 19, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps ZenHive/mpp (generic), ZenHive/mpp (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
ZenHive/mppgeneric	>=0.3.0 <0.6.3	0.6.3
ZenHive/mppgeneric	>=65b9e425ce27631c786a5b380b5e4c5ae607ec6d <ecc038088b1cda09ad8a84acc6cc112addb4a68f	ecc038088b1cda09ad8a84acc6cc112addb4a68f

Recommended response

Check inventory. Check lockfiles and deployed manifests for ZenHive/mpp, ZenHive/mpp.
Review the reported fix. Update ZenHive/mpp to 0.6.3; ZenHive/mpp to ecc038088b1cda09ad8a84acc6cc112addb4a68f if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 19, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.