mppx: Gas Draining with padding
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-63627
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 17:21 UTC · Revision 1
Source evidence
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.
osv:CVE-2026-63627
Complete source record
{
"id": "125916a9422f03b93fe9e26489bffc0f2d095403648e8b314f7266273e773ccf",
"url": "https://osv.dev/vulnerability/CVE-2026-63627",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "mppx: Gas Draining with padding",
"summary": "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.",
"evidence": "osv:CVE-2026-63627",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2026-63627",
"aliases": [
"CVE-2026-63627",
"GHSA-727h-3vm5-qwq6"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "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"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/wevm/mppx",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "831dd0a72aa35e5f7876b65ca4b4f8a645c9dc89"
},
{
"fixed": "24ddcca719ae282977d8747309ed1275ea282b25"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "0.8.2"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "24ddcca719ae282977d8747309ed1275ea282b25"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "831dd0a72aa35e5f7876b65ca4b4f8a645c9dc89"
}
],
"source": "REFERENCES_TAG",
"original_tag": "mppx@0.8.2"
}
]
}
}
],
"versions": [
"mppx@0.8.1",
"mppx@0.8.0",
"mppx@0.7.0",
"mppx@0.6.31",
"mppx@0.6.30",
"mppx@0.6.29",
"mppx@0.6.28",
"mppx@0.6.27",
"mppx@0.6.26",
"mppx@0.6.25",
"mppx@0.6.24",
"mppx@0.6.23",
"mppx@0.6.22",
"mppx@0.6.21",
"mppx@0.6.20",
"mppx@0.6.19",
"mppx@0.6.18",
"mppx@0.6.17",
"mppx@0.6.16",
"mppx@0.6.15",
"mppx@0.6.14",
"mppx@0.6.13",
"mppx@0.6.12",
"mppx@0.6.11",
"mppx@0.6.10",
"mppx@0.6.9",
"mppx@0.6.8",
"mppx@0.6.7",
"mppx@0.6.6",
"mppx@0.6.5",
"mppx@0.6.3",
"mppx@0.6.2",
"mppx@0.6.1",
"mppx@0.6.0",
"mppx@0.5.17",
"mppx@0.5.16",
"mppx@0.5.14",
"mppx@0.5.13",
"mppx@0.5.12",
"mppx@0.5.10",
"mppx@0.5.11",
"mppx@0.5.9",
"mppx@0.5.8",
"mppx@0.5.7",
"mppx@0.5.6",
"mppx@0.5.5",
"mppx@0.5.4",
"mppx@0.5.3",
"mppx@0.5.1",
"mppx@0.5.0",
"mppx@0.4.12",
"mppx@0.4.11",
"mppx@0.4.10",
"mppx@0.4.9",
"mppx@0.4.8",
"mppx@0.4.7",
"mppx@0.4.6",
"mppx@0.4.5",
"mppx@0.4.4",
"mppx@0.4.3",
"mppx@0.4.2",
"mppx@0.4.1",
"mppx@0.4.0",
"mppx@0.3.16",
"mppx@0.3.15",
"mppx@0.3.14",
"mppx@0.3.13",
"mppx@0.3.12",
"mppx@0.3.11",
"mppx@0.3.9",
"mppx@0.3.8",
"mppx@0.3.7",
"mppx@0.3.6",
"mppx@0.3.5",
"mppx@0.3.4",
"mppx@0.3.3",
"mppx@0.3.2",
"mppx@0.3.1",
"mppx@0.2.6",
"mppx@0.2.5",
"mppx@0.2.4",
"mppx@0.2.3",
"mppx@0.2.2",
"mppx@0.2.1",
"mppx@0.2.0",
"mppx@0.1.1",
"mppx@0.1.0",
"mpay@0.2.4",
"mpay@0.2.3",
"mpay@0.2.2",
"mpay@0.2.1",
"mpay@0.2.0",
"mpay@0.1.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63627.json"
}
}
],
"modified": "2026-10-28T02:30:37.813263509Z",
"provider": "osv",
"references": [
"https://github.com/wevm/mppx/releases/tag/mppx@0.8.2",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63627.json",
"https://github.com/wevm/mppx/security/advisories/GHSA-727h-3vm5-qwq6",
"https://nvd.nist.gov/vuln/detail/CVE-2026-63627",
"https://github.com/wevm/mppx/commit/24ddcca719ae282977d8747309ed1275ea282b25",
"https://github.com/wevm/mppx/pull/602"
],
"provider_metadata": {
"cwe_ids": [
"CWE-20"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63627.json"
}
},
"related_cves": [
{
"value": "CVE-2026-63627",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 505264,
"published_at": "2026-09-22T19:07:02.984+00:00"
}