GHSA-VV77-66RF-PM86
Vulnerability from github – Published: 2026-09-25 21:44 – Updated: 2026-09-25 21:44Details
When the server acts as the fee_payer, the mpp Elixir 0.4.0 does not validate gas_limit, max_fee_per_gas and max_priority_fee_per_gas before cosigning the client's fee-payer transaction. A malicious client embeds arbitrarily large max_fee_per_gas and max_priority_fee_per_gas values in the signed envelope. The server cosigns and broadcasts — paying those inflated gas costs from its own wallet based on the effective_gas_price calculated from the high max_fee_per_gas and max_priority_fee_per_gas set by the client.
Vulnerable function: cosign_fee_payer/3 in transaction.ex around lines 229–262.
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:
unzip mpp_elixir_PoC.zip
cd mpp_elixir
docker build -t mpp-elixir-gasdrain .
docker run --rm mpp-elixir-gasdrain
There are more details in mpp_elixir/README.md
Impact
By draining the server's wallet, an attacker causes direct financial loss to the organization. Furthermore, if the server's funds are drained completely, legitimate clients will have their requests fail, as the server can no longer fund future transactions, effectively creating a Denial of Service (DoS) attack.
{
"affected": [
{
"package": {
"ecosystem": "Hex",
"name": "mpp"
},
"ranges": [
{
"events": [
{
"introduced": "0.2.0"
},
{
"fixed": "0.6.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-20"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-25T21:44:12Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Details\nWhen the server acts as the fee_payer, the `mpp` Elixir 0.4.0 does not validate `gas_limit`, `max_fee_per_gas` and `max_priority_fee_per_gas` before cosigning the client\u0027s fee-payer transaction. A malicious client embeds arbitrarily large `max_fee_per_gas` and `max_priority_fee_per_gas` values in the signed envelope. The server cosigns and broadcasts \u2014 paying those inflated gas costs from its own wallet based on the `effective_gas_price` calculated from the high `max_fee_per_gas` and `max_priority_fee_per_gas` set by the client.\n\n**Vulnerable function:** `cosign_fee_payer/3` in [`transaction.ex`](https://hex.pm/packages/mpp/0.4.0) around lines 229\u2013262.\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-gasdrain .\ndocker run --rm mpp-elixir-gasdrain\n``` \nThere are more details in `mpp_elixir/README.md`\n\n### Impact\nBy draining the server\u0027s wallet, an attacker causes direct financial loss to the organization. Furthermore, if the server\u0027s funds are drained completely, legitimate clients will have their requests fail, as the server can no longer fund future transactions, effectively creating a Denial of Service (DoS) attack.",
"id": "GHSA-vv77-66rf-pm86",
"modified": "2026-09-25T21:44:12Z",
"published": "2026-09-25T21:44:12Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-vv77-66rf-pm86"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "mpp vulnerable to Gas Draining with no limit"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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