{"cve":"CVE-2026-63628","nvd":{"published":"2026-09-22T20:17:04.913","modified":"2026-09-24T15:17:26.803","status":"Awaiting Analysis","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.","cvss_v4":{"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","score":6.9},"cvss_v3":null,"cwes":["CWE-20"],"references":["https://github.com/wevm/mppx/commit/24ddcca719ae282977d8747309ed1275ea282b25","https://github.com/wevm/mppx/pull/602","https://github.com/wevm/mppx/releases/tag/mppx@0.8.2","https://github.com/wevm/mppx/security/advisories/GHSA-vc9j-9wph-qghj","https://github.com/wevm/mppx/security/advisories/GHSA-vc9j-9wph-qghj"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-63628","score":0.00487,"percentile":0.41952,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-vc9j-9wph-qghj","url":"https://osv.dev/vulnerability/GHSA-vc9j-9wph-qghj","summary":"mppx: Gas Draining with access list","modified":"2026-09-22T21:00:10.495528816Z","packages":[{"ecosystem":"npm","name":"mppx","purl":"pkg:npm/mppx","ranges":["<0.8.2"],"fixed":["0.8.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}