GHSA-qpxh-ff8m-c62v: Mpp Mpp Vulnerable To Gas Draining Vulnerability

MODERATE
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CWE-20
Published
Advisory Summary

GHSA-qpxh-ff8m-c62v is a MODERATE mpp vulnerable to gas draining vulnerability (CWE-20: Improper Input Validation) affecting Mpp libraries in the Hex ecosystem. The issue involves mpp vulnerable to gas draining with access list. Remediation is available by upgrading affected packages to version 0.6.0.

GHSA-qpxh-ff8m-c62v at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-qpxh-ff8m-c62v
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-20: Improper Input Validation
Affected Product Mpp
Package Ecosystem Hex
Published Date
Last Updated

How to Fix GHSA-qpxh-ff8m-c62v

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

mpp fixed: 0.6.0 
Upgrade mpp to 0.6.0
Verify Direct and Transitive Dependencies

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

inspect dependencies for mpp

How to Check if You Are Affected

To determine whether your application is affected by GHSA-qpxh-ff8m-c62v, inspect your project dependencies for Mpp:

inspect dependencies for mpp

Analyze the terminal output to locate any version of Mpp in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.6.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

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 Mpp, 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, `mpp` Elixir 0.4.0 copies the client-supplied EIP-2930 access list verbatim into the cosigned fee-payer transaction. In `cosign_fee_payer`, the server re-signs the raw `base_fields` (index 5 of the 0x76 AASigned envelope) without inspecting the access list field, which is part of the signed payload. 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 amount 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 137 entries and 100 Gwei `max_fee_per_gas`, this inflates the fee-payer cost from the normal ~51,287 gas to ~380,087 gas — a **7.4× multiplier** — while staying within Bandit's default 10,000-byte per-header-field limit (verified empirically). ### 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 mpp_elixir_PoC.zip cd mpp_elixir docker build -t mpp-elixir-access-list . docker run --rm mpp-elixir-access-list ``` There are more details in `mpp_elixir/README.md` ### Impact A malicious client can force the server to pay ~**7.4x** the normal transaction fee. This dramatically increases operational costs and completely destroys the profit margin on low-cost items.

GHSA-qpxh-ff8m-c62v Affected Mpp Versions

1 component(s)
Fixed Versions:
0.6.0
Product / Package Ecosystem Affected Versions Fixed Version
mpp
 Hex
≥ 0.2.0
< 0.6.0
0.6.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/ZenHive/mpp/security/advisories/GHSA-qpxh-ff8m-c62v
Security Fix Commit FIX COMMIT
https://github.com/ZenHive/mpp/commit/5d6338e2334084c5f2a78cfcca474830733ed7e8
Mpp Source Repository REPOSITORY
https://github.com/ZenHive/mpp
Mpp Release RELEASE
https://github.com/ZenHive/mpp/releases/tag/v0.6.0

Frequently Asked Questions

What is GHSA-qpxh-ff8m-c62v?
GHSA-qpxh-ff8m-c62v is a security vulnerability in Mpp involving mpp vulnerable to Gas Draining with access list under CWE-20: Improper Input Validation.
Which Mpp versions are affected?
Affected versions include releases prior to 0.6.0 across affected packages: mpp.
What version fixes GHSA-qpxh-ff8m-c62v?
Upgrading to 0.6.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is mpp affected?
Yes, mpp is affected in releases prior to 0.6.0. Upgrade your dependency to 0.6.0 or later.
What CWE is associated with GHSA-qpxh-ff8m-c62v?
GHSA-qpxh-ff8m-c62v 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 Hex dependencies for GHSA-qpxh-ff8m-c62v?
Run the dependency tree command: 'inspect dependencies for mpp'. 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-qpxh-ff8m-c62v",
  "modified" : "2026-09-25T21:45:16Z",
  "published" : "2026-09-25T21:45:16Z",
  "aliases" : [ ],
  "summary" : "mpp vulnerable to Gas Draining with access list",
  "details" : "### Details\nWhen the server acts as the fee_payer, `mpp` Elixir 0.4.0 copies the client-supplied EIP-2930 access list verbatim into the cosigned fee-payer transaction. In `cosign_fee_payer`, the server re-signs the raw `base_fields` (index 5 of the 0x76 AASigned envelope) without inspecting the access list field, which is part of the signed payload.\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 amount 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 137 entries and 100 Gwei `max_fee_per_gas`, this inflates the fee-payer cost from the normal ~51,287 gas to ~380,087 gas — a **7.4× multiplier** — while staying within Bandit's default 10,000-byte per-header-field limit (verified empirically).\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 mpp_elixir_PoC.zip\ncd mpp_elixir\ndocker build -t mpp-elixir-access-list .\ndocker run --rm mpp-elixir-access-list\n``` \nThere are more details in `mpp_elixir/README.md`\n\n### Impact\nA malicious client can force the server to pay ~**7.4x** the normal transaction fee. This dramatically increases operational costs and completely destroys the profit margin on low-cost items.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Hex",
      "name" : "mpp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.2.0"
      }, {
        "fixed" : "0.6.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/ZenHive/mpp/security/advisories/GHSA-qpxh-ff8m-c62v"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ZenHive/mpp/commit/5d6338e2334084c5f2a78cfcca474830733ed7e8"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ZenHive/mpp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ZenHive/mpp/releases/tag/v0.6.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-25T21:45:16Z",
    "nvd_published_at" : null
  }
}