CVE-2026-63627

mppx is a TypeScript interface for machine payments protocol. Prior to 0.8.2, FeePayerPolicy in src/tempo/internal/fee-payer.ts used decodeFunctionData to validate fee-sponsored calldata but did not reject trailing bytes. A client could append nonzero padding that increased intrinsic calldata gas while gas_limit and max_fee_per_gas remained within policy caps, causing the server fee_payer wallet to pay substantially more than the decoded transaction required. The tested 16 KB header limit bounded the demonstrated padding to about 5,500 bytes and produced approximately five times the normal transaction fee. This issue is fixed in version 0.8.2.

CVSS

No CVSS.

References

Link	Resource
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-727h-3vm5-qwq6

Configurations

No configuration.

History

22 Sep 2026, 20:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-22 20:17

Updated : 2026-09-23 18:12

NVD link : CVE-2026-63627

Mitre link : CVE-2026-63627

CVE.ORG link : CVE-2026-63627

JSON object : View

Products Affected

No product.

CWE

CWE-20

Improper Input Validation

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