Vulnerabilities in pkg:npm/mppx

PACKAGE
Advisory Identifier: GHSA-vc9j-9wph-qghj
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Advisory Summary

CVE-2026-63628 is a MODERATE gas draining with access list vulnerability (CWE-20: Improper Input Validation) affecting mppx libraries in the npm ecosystem. The issue involves gas draining with access list. Remediation is available by upgrading affected packages to version 0.8.2.

5 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/mppx

5 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:npm/mppx. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-vc9j-9wph-qghj CVE-2026-63628 MODERATE mppx: Gas Draining with access list
GHSA-727h-3vm5-qwq6 CVE-2026-63627 MODERATE mppx: Gas Draining with padding
GHSA-8mhj-rffc-rcvw CVE-2026-34210 MODERATE mppx has Stripe charge credential replay via missing idempotency check
GHSA-mv9j-8jvg-j8mr CVE-2026-34209 HIGH mppx: Tempo has a session close voucher bypass vulnerability due to settled amount equality
GHSA-8x4m-qw58-3pcx - CRITICAL mppx has multiple payment bypass and griefing vulnerabilities

CVE-2026-63628 at a Glance

CVE Identifier CVE-2026-63628
GHSA Identifier GHSA-vc9j-9wph-qghj
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-20: Improper Input Validation
Affected Product mppx
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-63628

To remediate this vulnerability, upgrade all affected mppx dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

mppx fixed: 0.8.2 
npm install mppx@0.8.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls mppx

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-63628, inspect your project dependencies using npm:

npm ls mppx

Analyze the terminal output to locate any version of mppx in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.8.2), your application is affected.

Note: The npm ls mppx command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In mppx, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Details When the server acts as the fee_payer, `mppx` 0.6.27 copies the client-supplied EIP-2930 access list verbatim into the cosigned fee-payer transaction. The TypeScript SDK's fee-payer cosigning path accepts any `access_list` the client includes in the 0x78 `FeePayerEnvelope` without inspecting its length or contents. Access list gas is charged **intrinsically** — before any opcode executes — regardless of whether the listed addresses are ever touched. An attacker submits a valid `transferWithMemo` alongside fabricated address-only access list entries. The server validates calldata and gas parameters but never inspects `access_list` length. It cosigns and broadcasts a transaction that costs the fee-payer wallet `N × 2,400` extra gas per request with no corresponding work performed on-chain. At the default of 180 entries and 100 Gwei `max_fee_per_gas`, this inflates the fee-payer cost from the normal ~51,287 gas to ~483,287 gas — a **9.4× multiplier** — while staying within the `FeePayerPolicy` cap of 500K gas, the Node.js 16 KB header limit, and the Moderato RPC's `eth_call` simulation budget (verified empirically at 180 entries). ### PoC The PoC is provided below. It is configured to reproduce the attack on Tempo Moderate testnet within a Docker environment. Download the PoC and run: ```bash unzip mppx_typescript_PoC.zip cd mppx_typescript docker build -t mppx-typescript-access-list . docker run --rm mppx-typescript-access-list ``` There are more details in `mppx_typescript/README.md` ### Impact A malicious client can force the server to pay ~**9.4x** the normal transaction fee. This dramatically increases operational costs and completely destroys the profit margin on low-cost items.

CVE-2026-63628 Affected mppx Versions

1 component(s)
Fixed Versions:
0.8.2
Product / Package Ecosystem Affected Versions Fixed Version
mppx
npm/mppx
npm
< 0.8.2
0.8.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/wevm/mppx/security/advisories/GHSA-vc9j-9wph-qghj
mppx Source Repository REPOSITORY
https://github.com/wevm/mppx/pull/602
Security Fix Commit FIX COMMIT
https://github.com/wevm/mppx/commit/24ddcca719ae282977d8747309ed1275ea282b25
mppx Source Repository REPOSITORY
https://github.com/wevm/mppx
mppx Release RELEASE
https://github.com/wevm/mppx/releases/tag/mppx@0.8.2

Frequently Asked Questions

What is CVE-2026-63628?
CVE-2026-63628 is a security vulnerability in mppx involving Gas Draining with access list under CWE-20: Improper Input Validation.
Which mppx versions are affected?
Affected versions include releases prior to 0.8.2 across affected packages: mppx.
What version fixes CVE-2026-63628?
Upgrading to 0.8.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is mppx affected?
Yes, mppx is affected in releases prior to 0.8.2. Upgrade your dependency to 0.8.2 or later.
What CWE is associated with CVE-2026-63628?
CVE-2026-63628 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check npm dependencies for CVE-2026-63628?
Run the dependency tree command: 'npm ls mppx'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vc9j-9wph-qghj",
  "modified" : "2026-09-22T20:34:19Z",
  "published" : "2026-09-22T20:34:19Z",
  "aliases" : [ "CVE-2026-63628" ],
  "summary" : "mppx: Gas Draining with access list",
  "details" : "### Details\nWhen the server acts as the fee_payer, `mppx` 0.6.27 copies the client-supplied EIP-2930 access list verbatim into the cosigned fee-payer transaction. The TypeScript SDK's fee-payer cosigning path accepts any `access_list` the client includes in the 0x78 `FeePayerEnvelope` without inspecting its length or contents.\n\nAccess list gas is charged **intrinsically** — before any opcode executes — regardless of whether the listed addresses are ever touched.\n\nAn attacker submits a valid `transferWithMemo` alongside fabricated address-only access list entries. The server validates calldata and gas parameters but never inspects `access_list` length. It cosigns and broadcasts a transaction that costs the fee-payer wallet `N × 2,400` extra gas per request with no corresponding work performed on-chain.\n\nAt the default of 180 entries and 100 Gwei `max_fee_per_gas`, this inflates the fee-payer cost from the normal ~51,287 gas to ~483,287 gas — a **9.4× multiplier** — while staying within the `FeePayerPolicy` cap of 500K gas, the Node.js 16 KB header limit, and the Moderato RPC's `eth_call` simulation budget (verified empirically at 180 entries).\n\n### PoC\nThe PoC is provided below. It is configured to reproduce the attack on Tempo Moderate testnet within a Docker environment. Download the PoC and run:\n```bash\nunzip mppx_typescript_PoC.zip\ncd mppx_typescript\ndocker build -t mppx-typescript-access-list .\ndocker run --rm mppx-typescript-access-list\n``` \nThere are more details in `mppx_typescript/README.md`\n\n### Impact\nA malicious client can force the server to pay ~**9.4x** the normal transaction fee. This dramatically increases operational costs and completely destroys the profit margin on low-cost items.",
  "severity" : [ ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "mppx"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.8.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/wevm/mppx/security/advisories/GHSA-vc9j-9wph-qghj"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/wevm/mppx/pull/602"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/wevm/mppx/commit/24ddcca719ae282977d8747309ed1275ea282b25"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/wevm/mppx"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/wevm/mppx/releases/tag/mppx@0.8.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-22T20:34:19Z",
    "nvd_published_at" : null
  }
}