mppx is a TypeScript interface for machine payments protocol. Prior to 0.8.2, the fee-payer cosigning path in src/tempo/internal/fee-payer.ts copied a client-supplied access_list from a 0x78 FeePayerEnvelope without validating its length or contents. Because EIP-2930 access-list entries consume intrinsic gas even when the listed addresses are never used, a client could add fabricated address-only entries and cause the server fee_payer wallet to pay unnecessary transaction fees. The demonstrated 180-entry list remained within the 500,000 gas policy cap, 16 KB header limit, and RPC simulation budget while increasing the fee by approximately 9.4 times. This issue is fixed in version 0.8.2.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-vc9j-9wph-qghj mppx: Gas Draining with access list
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 22 Sep 2026 21:00:00 +0000

Type Values Removed Values Added
First Time appeared Wevm
Wevm mppx
Vendors & Products Wevm
Wevm mppx

Tue, 22 Sep 2026 19:30:00 +0000

Type Values Removed Values Added
Description mppx is a TypeScript interface for machine payments protocol. Prior to 0.8.2, the fee-payer cosigning path in src/tempo/internal/fee-payer.ts copied a client-supplied access_list from a 0x78 FeePayerEnvelope without validating its length or contents. Because EIP-2930 access-list entries consume intrinsic gas even when the listed addresses are never used, a client could add fabricated address-only entries and cause the server fee_payer wallet to pay unnecessary transaction fees. The demonstrated 180-entry list remained within the 500,000 gas policy cap, 16 KB header limit, and RPC simulation budget while increasing the fee by approximately 9.4 times. This issue is fixed in version 0.8.2.
Title mppx: Gas Draining with access list
Weaknesses CWE-20
References
Metrics cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-22T19:09:38.414Z

Reserved: 2026-07-17T14:11:15.482Z

Link: CVE-2026-63628

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-22T20:17:04.913

Modified: 2026-09-22T20:17:04.913

Link: CVE-2026-63628

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-22T20:45:16Z

Weaknesses