CVE-2026-63628
mppx is a TypeScript interface for machine payments protocol.
Does this matter?
Lower severity and a low EPSS score (0.49%). Track it; it rarely justifies an emergency change on its own.
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 4.0
- 6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.49% probability · 42th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-20
- Source
- security-advisories@github.com
EPSS moved from 0.5% on 23 September 2026 to 0.5% on 26 October 2026.
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.