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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "pympp",
          "vendor": "tempoxyz",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.9.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "pympp is a Python SDK for the Machine Payments Protocol. Prior to version 0.9.1, when the server acts as the fee_payer, pympp validates calldata using eth_abi decoding, which is lenient about trailing bytes. The FeePayerPolicy caps gas_limit (\u2264 2 M) and max_fee_per_gas (\u2264 100 Gwei) but does not check calldata length. Tempo uses legacy calldata gas pricing: 16 gas per non-zero byte. Appending N bytes of 0x01 padding inflates actual gas used by N \u00d7 16 while keeping gas_limit and max_fee_per_gas within policy caps. The server cosigns and broadcasts the padded transaction, draining its fee-payer wallet. This issue has been patched in version 0.9.1."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 6.9,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-20",
              "description": "CWE-20: Improper Input Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-09T20:59:55.768Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/tempoxyz/pympp/security/advisories/GHSA-v858-xh7w-8jr5",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/tempoxyz/pympp/security/advisories/GHSA-v858-xh7w-8jr5"
        },
        {
          "name": "https://github.com/tempoxyz/pympp/commit/57a750d0d980b8e6c3bea62a40b7621f176ff1f0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/tempoxyz/pympp/commit/57a750d0d980b8e6c3bea62a40b7621f176ff1f0"
        },
        {
          "name": "https://github.com/tempoxyz/pympp/releases/tag/v0.9.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/tempoxyz/pympp/releases/tag/v0.9.1"
        }
      ],
      "source": {
        "advisory": "GHSA-v858-xh7w-8jr5",
        "discovery": "UNKNOWN"
      },
      "title": "pympp: Gas Draining with padding"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-63634",
    "datePublished": "2026-11-09T20:59:55.768Z",
    "dateReserved": "2026-07-17T14:11:15.482Z",
    "dateUpdated": "2026-11-09T20:59:55.768Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}